scripts: config_whitelist: drop CONFIG_MMCROOT

Drop CONFIG_MMCROOT, no users now.

Reviewed-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index 3233a83..be597f7 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -416,7 +416,6 @@
 CONFIG_MISC_COMMON
 CONFIG_MIU_2BIT_21_7_INTERLEAVED
 CONFIG_MIU_2BIT_INTERLEAVED
-CONFIG_MMCROOT
 CONFIG_MMC_DEFAULT_DEV
 CONFIG_MMC_SUNXI_SLOT
 CONFIG_MONITOR_IS_IN_RAM