[PATCH] dvb: core: demux error handling fix

In dvb_dmxdev_filter_start if we go out because of an error, release
previously allocated demux_feed.

Signed-off-by: Peter Beutner <p.beutner@gmx.net>
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>