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/uniphier_v7_defconfig b/configs/uniphier_v7_defconfig
index 89b7b4a..8dae587 100644
--- a/configs/uniphier_v7_defconfig
+++ b/configs/uniphier_v7_defconfig
@@ -38,6 +38,7 @@
 CONFIG_I2C_EEPROM=y
 CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS=10
 CONFIG_MMC_UNIPHIER=y
+CONFIG_MTD_DEVICE=y
 CONFIG_NAND=y
 CONFIG_NAND_DENALI_DT=y
 CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES=8