media: hantro: Simplify the controls creation logic

v4l2_ctrl_new_custom() should work for any kind of control, including
standard ones. With that change, we automatically get support for
menu controls.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>