media: rkvdec: Restore iommu addresses on errors

On errors, the rkvdec chip self resets. This can clear the addresses
programmed in the iommu. This case is signaled by the
RKVDEC_SOFTRESET_RDY status bit.

Since the iommu framework does not have a restore functionality, and
as recommended by the iommu subsystem maintainers, this patch
restores the iommu programming by attaching and detaching an empty
domain, which will clear and restore the default domain.

Suggested-by: Detlev Casanova <detlev.casanova@collabora.com>
Tested-by: Detlev Casanova <detlev.casanova@collabora.com>
Reviewed-by: Detlev Casanova <detlev.casanova@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>