media: ddbridge: add helper for IRQ handler setup

Introduce the ddb_irq_set() helper function (along with a matching
prototype in ddbridge.h) to improve the set up of the IRQ handlers
and handler_data, and rework storing this data into the ddb_link
using a new ddb_irq struct. This also does the necessary rework
of affected variables. And while at it, always do queue_work in
input_handler() as there's not much of a difference to directly
calling input_work if there's no ptr at input->redi, or queueing
this call.

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>