mtd: Rename SPL_MTD_SUPPORT to SPL_MTD

Rename SPL_MTD_SUPPORT to SPL_MTD in order to match MTD. This allows using
CONFIG_IS_ENABLED to test for MTD support.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/configs/am335x_hs_evm_uart_defconfig b/configs/am335x_hs_evm_uart_defconfig
index b5d8eac..7886557 100644
--- a/configs/am335x_hs_evm_uart_defconfig
+++ b/configs/am335x_hs_evm_uart_defconfig
@@ -29,7 +29,7 @@
 CONFIG_SPL_FIT_IMAGE_TINY=y
 # CONFIG_SPL_ENV_SUPPORT is not set
 # CONFIG_SPL_FS_EXT4 is not set
-CONFIG_SPL_MTD_SUPPORT=y
+CONFIG_SPL_MTD=y
 # CONFIG_SPL_NAND_SUPPORT is not set
 CONFIG_SPL_NAND_DRIVERS=y
 CONFIG_SPL_NAND_ECC=y