spi: Rename SPI_SUPPORT to SPI

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/axm_defconfig b/configs/axm_defconfig
index 049c960..eae53eb 100644
--- a/configs/axm_defconfig
+++ b/configs/axm_defconfig
@@ -25,7 +25,7 @@
 CONFIG_DEBUG_UART_CLOCK=18432000
 CONFIG_ENV_OFFSET_REDUND=0x180000
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
-CONFIG_SPL_SPI_SUPPORT=y
+CONFIG_SPL_SPI=y
 CONFIG_DEBUG_UART=y
 CONFIG_SYS_LOAD_ADDR=0x22000000
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9G20,MACH_TYPE=2068"