media: v4l2-tpg: Clamp hue in tpg_s_hue()

Setting `hue` by calling tpg_s_hue() directly is risky, since it does not
perform range check. Clamp `hue` to the valid range in tpg_s_hue().

Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>