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/brppt1_spi_defconfig b/configs/brppt1_spi_defconfig
index 826a93c..3651bab 100644
--- a/configs/brppt1_spi_defconfig
+++ b/configs/brppt1_spi_defconfig
@@ -81,6 +81,7 @@
 CONFIG_DM_MMC=y
 CONFIG_MMC_OMAP_HS=y
 CONFIG_DM_SPI_FLASH=y
+CONFIG_MTD_DEVICE=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_WINBOND=y