media: aspeed: refine interrupt handling logic

There are cases that interrupt bits are cleared by a 500ms delayed
work which causes unnecessary irq calls. Also, the current
interrupt handler returns IRQ_HANDLED always but it should return
IRQ_NONE if there is any unhandled interrupt. So this commit
refines the interrupt handling logic to fix these issues.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>