mmc: Convert to use ATTRIBUTE_GROUPS

Use new ATTRIBUTE_GROUPS macro to declare attribute groups.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index e22d851..fbcf93d 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -694,18 +694,10 @@
 	&dev_attr_rel_sectors.attr,
 	NULL,
 };
-
-static struct attribute_group mmc_std_attr_group = {
-	.attrs = mmc_std_attrs,
-};
-
-static const struct attribute_group *mmc_attr_groups[] = {
-	&mmc_std_attr_group,
-	NULL,
-};
+ATTRIBUTE_GROUPS(mmc_std);
 
 static struct device_type mmc_type = {
-	.groups = mmc_attr_groups,
+	.groups = mmc_std_groups,
 };
 
 /*