vmdk: vmdk_read_cid returns garbage if p_name is NULL

Spotted by Clang Analyzer
Signed-off-by: NPavel Borzenkov <pavel.borzenkov@gmail.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

block/vmdk.c

@@ -207,7 +207,7 @@ static void vmdk_free_last_extent(BlockDriverState *bs)
 static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent)
 {
     char desc[DESC_SIZE];
-    uint32_t cid;
+    uint32_t cid = 0xffffffff;
     const char *p_name, *cid_str;
     size_t cid_str_size;
     BDRVVmdkState *s = bs->opaque;