configs: Migrate and re-enabled CONFIG_CMD_MTDPARTS

Now that CMD_UBI does not select CMD_MTDPARTS we need to make platforms
that had been enabling it turn it on by hand.  This exposed that we had
not yet migrated CMD_MTDPARTS fully, so do so now.

Fixes: 86dfa556d927 ("cmd: ubi: Remove useless call to mtdparts_init()")
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/platinum_picon_defconfig b/configs/platinum_picon_defconfig
index 16f1309..91487c1 100644
--- a/configs/platinum_picon_defconfig
+++ b/configs/platinum_picon_defconfig
@@ -40,6 +40,7 @@
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
+CONFIG_CMD_MTDPARTS=y
 CONFIG_MTDIDS_DEFAULT="nand0=gpmi-nand"
 CONFIG_MTDPARTS_DEFAULT="mtdparts=gpmi-nand:14M(spl),2M(uboot),512k(env1),512k(env2),495M(ubi0),14M(res0),2M(res1),512k(res2),512k(res3),-(ubi1)"
 CONFIG_CMD_UBI=y