The flexcop chip often stops generating interrupts after some hours of
operation.  Apparently this can be fixed by resetting register block 0x300 at
each channel change (this is not detailed in the flexcop data books).

This patch also restructures DMA handling and adds a bit of debug code for the
irq problem in case it still happens for someone.
Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>