memory: Move TI_AEMIF config to KCONFIG

Not all Keystone2 devices has AEMIF NAND controller. So adding Kconfig
entry for CONFIG_TI_AEMIF and enabling it in respective defconfigs on
platforms with AEMIF controller.

Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

drivers/Kconfig

@@ -30,6 +30,8 @@ source "drivers/input/Kconfig"
 
 source "drivers/led/Kconfig"
 
+source "drivers/memory/Kconfig"
+
 source "drivers/misc/Kconfig"
 
 source "drivers/mmc/Kconfig"