Convert CONFIG_MTD_PARTITIONS et al to Kconfig

This converts the following to Kconfig:
   CONFIG_MTD_PARTITIONS
   CONFIG_MTD_DEVICE

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/am335x_evm_norboot_defconfig b/configs/am335x_evm_norboot_defconfig
index ea0eebb..1d7233e 100644
--- a/configs/am335x_evm_norboot_defconfig
+++ b/configs/am335x_evm_norboot_defconfig
@@ -23,6 +23,7 @@
 CONFIG_USB_FUNCTION_FASTBOOT=y
 CONFIG_MMC_OMAP_HS=y
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_MTD_DEVICE=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_DRIVER_TI_CPSW=y