Correct CHECK_MEM_ERROR macro

The previous macro doesn't work with &cpi->common as a first argument

Change-Id: Ic3f5c49a94cf8b17de6569811b957c963341bb58
diff --git a/vp9/common/vp9_common.h b/vp9/common/vp9_common.h
index 577fa68..a4111fc 100644
--- a/vp9/common/vp9_common.h
+++ b/vp9/common/vp9_common.h
@@ -51,7 +51,7 @@
   do {                                                                      \
     lval = (expr);                                                          \
     if (!lval)                                                              \
-      vpx_internal_error(&cm->error, VPX_CODEC_MEM_ERROR,                   \
+      vpx_internal_error(&(cm)->error, VPX_CODEC_MEM_ERROR,                 \
                          "Failed to allocate " #lval " at %s:%d", __FILE__, \
                          __LINE__);                                         \
   } while (0)