mx6slevk: Fix the boot device number

The SD card is registered as mmc device 0.

Fix it accordingly so that the board can boot to Linux
from the SD card.

Signed-off-by: Fabio Estevam <festevam@denx.de>

configs/mx6slevk_defconfig

@@ -38,7 +38,6 @@ CONFIG_OF_CONTROL=y
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
-CONFIG_SYS_MMC_ENV_DEV=1
 CONFIG_BOUNCE_BUFFER=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MXC=y

include/configs/mx6slevk.h

@@ -25,9 +25,9 @@
 	"fdt_addr=0x88000000\0" \
 	"boot_fdt=try\0" \
 	"ip_dyn=yes\0" \
-	"mmcdev=1\0" \
+	"mmcdev=0\0" \
 	"mmcpart=1\0" \
-	"finduuid=part uuid mmc 1:2 uuid\0" \
+	"finduuid=part uuid mmc ${mmcdev}:2 uuid\0" \
 	"mmcargs=setenv bootargs console=${console},${baudrate} " \
 		"root=PARTUUID=${uuid} rootwait rw\0" \
 	"loadbootscript=" \