mtd: rawnand: denali: set SPARE_AREA_SKIP_BYTES based on DT compatible

Currently, the denali NAND driver in U-Boot configures the
SPARE_AREA_SKIP_BYTES based on the CONFIG option.

Recently, Linux kernel merged a patch that associates the proper
value for this register with the DT compatible string.

Do likewise in U-Boot too.

The denali_spl.c still uses CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
index 8537c60..be1b362 100644
--- a/drivers/mtd/nand/raw/denali.c
+++ b/drivers/mtd/nand/raw/denali.c
@@ -1069,11 +1069,18 @@
 		denali->revision = swab16(ioread32(denali->reg + REVISION));
 
 	/*
-	 * tell driver how many bit controller will skip before writing
-	 * ECC code in OOB. This is normally used for bad block marker
+	 * Set how many bytes should be skipped before writing data in OOB.
+	 * If a platform requests a non-zero value, set it to the register.
+	 * Otherwise, read the value out, expecting it has already been set up
+	 * by firmware.
 	 */
-	denali->oob_skip_bytes = CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES;
-	iowrite32(denali->oob_skip_bytes, denali->reg + SPARE_AREA_SKIP_BYTES);
+	if (denali->oob_skip_bytes)
+		iowrite32(denali->oob_skip_bytes,
+			  denali->reg + SPARE_AREA_SKIP_BYTES);
+	else
+		denali->oob_skip_bytes = ioread32(denali->reg +
+						  SPARE_AREA_SKIP_BYTES);
+
 	denali_detect_max_banks(denali);
 	iowrite32(0x0F, denali->reg + RB_PIN_ENABLED);
 	iowrite32(CHIP_EN_DONT_CARE__FLAG, denali->reg + CHIP_ENABLE_DONT_CARE);