[media] pxa_camera: fix error return code in pxa_camera_probe()

Fix to return error code -ENODEV from dma_request_slave_channel_compat()
error handling case instead of 0, as done elsewhere in this function.

Also fix to release resources in v4l2_clk_register() error handling.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>