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_norboot_defconfig b/configs/am335x_evm_norboot_defconfig
index 7dbfa27..d2d3ba2 100644
--- a/configs/am335x_evm_norboot_defconfig
+++ b/configs/am335x_evm_norboot_defconfig
@@ -1,4 +1,5 @@
-CONFIG_SYS_EXTRA_OPTIONS="NOR,NOR_BOOT"
+CONFIG_SYS_EXTRA_OPTIONS="NOR_BOOT"
 CONFIG_CONS_INDEX=1
 CONFIG_ARM=y
 CONFIG_TARGET_AM335X_EVM=y
+CONFIG_NOR=y