Add workaround for signal lock loss issue, where the frontend loses the signal
after some hours without any visible reason.
Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.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>