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/P1021RDB-PC_SDCARD_defconfig b/configs/P1021RDB-PC_SDCARD_defconfig
index 5c2913e..8398bb89 100644
--- a/configs/P1021RDB-PC_SDCARD_defconfig
+++ b/configs/P1021RDB-PC_SDCARD_defconfig
@@ -41,6 +41,7 @@
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_FSL_ESDHC=y
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_MTD_PARTITIONS=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_PHY_MARVELL=y