media: fix secfeed undefined when filter alloc fail

  In dvb_dmxdev_filter_start, when secfeed allocate secfilter fail.
  the secfeed of current dmxfilter, need set to NULL;
  Instead of call start_filtering, which already handled in
  dvb_dmxdev_feed_restart

Signed-off-by: jieqing.wang <standback@126.com>
Link: https://lore.kernel.org/r/20221201052705.2313911-1-standback@126.com
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/dvb-core/dmxdev.c

@@ -731,7 +731,7 @@ static int dvb_dmxdev_filter_start(struct dmxdev_filter *filter)
 		ret = (*secfeed)->allocate_filter(*secfeed, secfilter);
 		if (ret < 0) {
 			dvb_dmxdev_feed_restart(filter);
-			filter->feed.sec->start_filtering(*secfeed);
+			*secfeed = NULL;
 			dprintk("could not get filter\n");
 			return ret;
 		}