ARM: configs: keystone: add MTD_SPI_NOR (new dependency for M25P80)

This defconfig contains the CONFIG_M25P80 symbol, which is now
dependent on the MTD_SPI_NOR symbol. Add CONFIG_MTD_SPI_NOR to satisfy
the new dependency.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm/configs/keystone_defconfig

@@ -112,6 +112,7 @@ CONFIG_MTD_PLATRAM=y
 CONFIG_MTD_M25P80=y
 CONFIG_MTD_NAND=y
 CONFIG_MTD_NAND_DAVINCI=y
+CONFIG_MTD_SPI_NOR=y
 CONFIG_MTD_UBI=y
 CONFIG_PROC_DEVICETREE=y
 CONFIG_BLK_DEV_LOOP=y