mtd: spi-nor: Use CONFIG_IS_ENABLED for CONFIG_SPI_FLASH_BAR defines

At the moment a mixture of ifdef(CONFIG_IS_ENABLED) and
CONFIG_IS_ENABLED(SPI_FLASH_BAR) is used in the spi-nor framework.
This leads to misbehaviour in the SPL as there is no Kconfig option
CONFIG_SPL_SPI_FLASH_BAR. This commit standardizes the use of
CONFIG_SPI_FLASH to get SPLs that load U-Boot proper from the
SPI flash to work again.

Fixes: 9bb02f7 (mtd: spi-nor: Fix the spi_nor_read() when config SPI_STACKED_PARALLEL is enabled)
Signed-off-by: Bernhard Messerklinger <bernhard.messerklinger@br-automation.com>
diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 6f352c5..a8865bb 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -655,7 +655,7 @@
 	return mtd->priv;
 }
 
-#ifndef CONFIG_SPI_FLASH_BAR
+#if !CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 static u8 spi_nor_convert_opcode(u8 opcode, const u8 table[][2], size_t size)
 {
 	size_t i;
@@ -739,7 +739,7 @@
 	nor->program_opcode = spi_nor_convert_3to4_program(nor->program_opcode);
 	nor->erase_opcode = spi_nor_convert_3to4_erase(nor->erase_opcode);
 }
-#endif /* !CONFIG_SPI_FLASH_BAR */
+#endif /* !CONFIG_IS_ENABLED(SPI_FLASH_BAR) */
 
 /* Enable/disable 4-byte addressing mode. */
 static int set_4byte(struct spi_nor *nor, const struct flash_info *info,
@@ -930,7 +930,7 @@
 	return spi_nor_wait_till_ready_with_timeout(nor, timeout);
 }
 
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 /*
  * This "clean_bar" is necessary in a situation when one was accessing
  * spi flash memory > 16 MiB by using Bank Address Register's BA24 bit.
@@ -1141,7 +1141,7 @@
 					nor->spi->flags &= ~SPI_XFER_U_PAGE;
 			}
 		}
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 		ret = write_bar(nor, offset);
 		if (ret < 0)
 			goto erase_err;
@@ -1175,7 +1175,7 @@
 
 	addr_known = false;
 erase_err:
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 	err = clean_bar(nor);
 	if (!ret)
 		ret = err;
@@ -1630,7 +1630,7 @@
 				offset /= 2;
 		}
 
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 		ret = write_bar(nor, offset);
 		if (ret < 0)
 			return log_ret(ret);
@@ -1667,7 +1667,7 @@
 	ret = 0;
 
 read_err:
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 	ret = clean_bar(nor);
 #endif
 	return ret;
@@ -2016,7 +2016,7 @@
 			}
 		}
 
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 		ret = write_bar(nor, offset);
 		if (ret < 0)
 			return ret;
@@ -2090,7 +2090,7 @@
 	}
 
 write_err:
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 	ret = clean_bar(nor);
 #endif
 	return ret;
@@ -3791,7 +3791,7 @@
 	int ret;
 	u8 cr;
 
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 	return -ENOTSUPP; /* Bank Address Register is not supported */
 #endif
 	/*
@@ -4577,7 +4577,7 @@
 	if (nor->flags & (SNOR_F_HAS_PARALLEL | SNOR_F_HAS_STACKED))
 		shift = 1;
 	if (nor->addr_width == 3 && (mtd->size >> shift) > SZ_16M) {
-#ifndef CONFIG_SPI_FLASH_BAR
+#if !CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 		/* enable 4-byte addressing if the device exceeds 16MiB */
 		nor->addr_width = 4;
 		if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index b8b207f..4eef4ab 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -569,7 +569,7 @@
 	u8			rdsr_dummy;
 	u8			rdsr_addr_nbytes;
 	u8			addr_mode_nbytes;
-#ifdef CONFIG_SPI_FLASH_BAR
+#if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
 	u8			bank_read_cmd;
 	u8			bank_write_cmd;
 	u8			bank_curr;