Save environment data to mmc.

This patch is to save environment data to mmc card.
It uses interfaces defined in generic mmc.

Signed-off-by: Terry Lv <r65388@freescale.com>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index fd5320d..c941b95 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -59,13 +59,14 @@
     !defined(CONFIG_ENV_IS_IN_FLASH)	&& \
     !defined(CONFIG_ENV_IS_IN_DATAFLASH)	&& \
     !defined(CONFIG_ENV_IS_IN_MG_DISK)	&& \
+    !defined(CONFIG_ENV_IS_IN_MMC)  && \
     !defined(CONFIG_ENV_IS_IN_NAND)	&& \
     !defined(CONFIG_ENV_IS_IN_NVRAM)	&& \
     !defined(CONFIG_ENV_IS_IN_ONENAND)	&& \
     !defined(CONFIG_ENV_IS_IN_SPI_FLASH)	&& \
     !defined(CONFIG_ENV_IS_NOWHERE)
 # error Define one of CONFIG_ENV_IS_IN_{EEPROM|FLASH|DATAFLASH|ONENAND|\
-SPI_FLASH|MG_DISK|NVRAM|NOWHERE}
+SPI_FLASH|MG_DISK|NVRAM|MMC|NOWHERE}
 #endif
 
 #define XMK_STR(x)	#x