avfilter/vf_sr: correct flags since the filter changes frame w/h

If filter changes frame w/h, AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
cannot be supported.

Signed-off-by: Guo, Yejun <yejun.guo@intel.com>
Signed-off-by: Pedro Arthur <bygrandao@gmail.com>

libavfilter/vf_sr.c

@@ -317,5 +317,4 @@ AVFilter ff_vf_sr = {
     .inputs        = sr_inputs,
     .outputs       = sr_outputs,
     .priv_class    = &sr_class,
-    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
 };