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_spiboot_defconfig b/configs/am335x_evm_spiboot_defconfig
index 9408f04..c36fabd 100644
--- a/configs/am335x_evm_spiboot_defconfig
+++ b/configs/am335x_evm_spiboot_defconfig
@@ -27,6 +27,7 @@
 CONFIG_DFU_RAM=y
 CONFIG_USB_FUNCTION_FASTBOOT=y
 CONFIG_MMC_OMAP_HS=y
+CONFIG_MTD_DEVICE=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_DRIVER_TI_CPSW=y