vdi: Fix memory leak

The block map is allocated in vdi_open, but was never freed.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/vdi.c

@@ -949,6 +949,9 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options)
 static void vdi_close(BlockDriverState *bs)
 {
     BDRVVdiState *s = bs->opaque;
+
+    g_free(s->bmap);
+
     migrate_del_blocker(s->migration_blocker);
     error_free(s->migration_blocker);
 }