Improve IRQ handling in the separated MSG/I2C and IO/TSDATA handlers by
applying a mask for recognized bits immediately upon reading the IRQ mask
from the hardware, so only the bits/IRQs that actually were set will be
acked.

Picked up from the upstream dddvb-0.9.33 release.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>