Merge pull request #657 from yatharth-arm/yk/genfw-1505

Fix `cert_create` tool for Segmentation fault

tools/cert_create/src/main.c

@@ -428,9 +428,11 @@ int main(int argc, char *argv[])
 			 */
 			switch (ext->type) {
 			case EXT_TYPE_NVCOUNTER:
+				if (ext->arg) {
 					nvctr = atoi(ext->arg);
 					CHECK_NULL(cert_ext, ext_new_nvcounter(ext_nid,
 						EXT_CRIT, nvctr));
+				}
 				break;
 			case EXT_TYPE_HASH:
 				if (ext->arg == NULL) {