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/wb45n_defconfig b/configs/wb45n_defconfig
index f52d46e..eb6a921 100644
--- a/configs/wb45n_defconfig
+++ b/configs/wb45n_defconfig
@@ -25,5 +25,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_NAND=y
 CONFIG_NAND_ATMEL=y
+CONFIG_MTD_DEVICE=y
+CONFIG_MTD_PARTITIONS=y
 CONFIG_LZMA=y
 CONFIG_OF_LIBFDT=y