The ARM IOMMU mapping needs to be released when attaching the device
fails. Add arm_iommu_release_mapping() to the error code path. This is
safe to call with a NULL mapping, so no specific check is needed.

Cleanup is also missing when failing to create a mapping. Jump to the
error code path in that case instead of returning immediately.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>