sunxi-csi: fill in bus_info of media device

This fixes a v4l2-compliance warning:

Required ioctls:
                warn: v4l2-test-media.cpp(52): empty bus_info
        test MEDIA_IOC_DEVICE_INFO: OK

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>