Fix rild at_get_cme_error bug.

Change-Id: I7ee0bee5e071d16709217c5408cee053d27dd63c
diff --git a/mbtk/mbtk_rild_v2/src/atchannel.c b/mbtk/mbtk_rild_v2/src/atchannel.c
index 54313d0..3a69ad9 100755
--- a/mbtk/mbtk_rild_v2/src/atchannel.c
+++ b/mbtk/mbtk_rild_v2/src/atchannel.c
@@ -1313,6 +1313,11 @@
     int err;
     char *p_cur;
 
+    if (p_response == NULL)
+    {
+        return CME_ERROR_NON_CME;
+    }
+
     if (p_response->success > 0)
     {
         return CME_SUCCESS;