am335x_evm: Add NOR to Kconfig

Make enabling support for NOR (and describe where it's seen) be done via
Kconfig.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/configs/am335x_evm_nor_defconfig b/configs/am335x_evm_nor_defconfig
index 41f31cc..be90163 100644
--- a/configs/am335x_evm_nor_defconfig
+++ b/configs/am335x_evm_nor_defconfig
@@ -1,5 +1,6 @@
 CONFIG_SPL=y
-CONFIG_SYS_EXTRA_OPTIONS="NAND,NOR"
+CONFIG_SYS_EXTRA_OPTIONS="NAND"
 CONFIG_CONS_INDEX=1
 +S:CONFIG_ARM=y
 +S:CONFIG_TARGET_AM335X_EVM=y
+CONFIG_NOR=y