parallels: Use bdrv_co_getlength() in parallels_check_outside_image()

bdrv_co_getlength() should be used in coroutine context. Replace
bdrv_getlength() by bdrv_co_getlength() in parallels_check_outside_image().

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Denis V. Lunev <den@openvz.org>

block/parallels.c

@@ -500,7 +500,7 @@ parallels_check_leak(BlockDriverState *bs, BdrvCheckResult *res,
     int64_t size;
     int ret;
 
-    size = bdrv_getlength(bs->file->bs);
+    size = bdrv_co_getlength(bs->file->bs);
     if (size < 0) {
         res->check_errors++;
         return size;