cmd: mmc: check whether card is SD or eMMC before hwpartition

It doesn't need to follow more sequence to do the hwparititioning,
because SD doesn't support hwpartitioning feature.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/cmd/mmc.c b/cmd/mmc.c
index 64e6be7..96d81ff 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -698,6 +698,11 @@
 	if (!mmc)
 		return CMD_RET_FAILURE;
 
+	if (IS_SD(mmc)) {
+		puts("SD doesn't support partitioning\n");
+		return CMD_RET_FAILURE;
+	}
+
 	if (argc < 1)
 		return CMD_RET_USAGE;
 	i = 1;