[media] lmedm04: rs2000 check if interrupt urb is over due

Change handling of signal_lock on rs2000. Use ibuf[2] to detect
lock as there is a longer wait for lock to appear in ibuf[6].

Remove last_key and key_timeout and use jiffies plus 60ms
to detect that streaming is still active.

If the current jiffies is time_after the interrupt urb overdue and
clear signal lock.

This results in far faster recovery of lock and streaming.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>