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/sd.c b/drivers/mmc/core/sd.c
index 2dd359d..aef5157 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -707,18 +707,10 @@
 	&dev_attr_serial.attr,
 	NULL,
 };
-
-static struct attribute_group sd_std_attr_group = {
-	.attrs = sd_std_attrs,
-};
-
-static const struct attribute_group *sd_attr_groups[] = {
-	&sd_std_attr_group,
-	NULL,
-};
+ATTRIBUTE_GROUPS(sd_std);
 
 struct device_type sd_type = {
-	.groups = sd_attr_groups,
+	.groups = sd_std_groups,
 };
 
 /*