[media] adv7180: Use threaded IRQ instead of IRQ + workqueue

The proper way to handle IRQs that need to be able to sleep in their IRQ handler
is to use a threaded IRQ.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>