media: rcar-vin: Fold rvin_initialize_device() into rvin_open()

The function no longer serve a purpose as most tasks it performed have
been refactored, fold what remains of it into the only caller. While at
it add error checking for v4l2_ctrl_handler_setup().

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>