media: cx25821: request_irq -> devm_request_irq

Fixes smatch warning:

drivers/media/pci/cx25821/cx25821-alsa.c:768 cx25821_audio_initdev() warn: 'dev->pci->irq' from request_irq() not released on lines: 768.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>