V4L/DVB: tvp514x: simplify try/g/s_fmt handling

Since there is only one possible format just have all three calls
do the same.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Reviewed-by: Vaibhav Hiremath <hvaibhav@ti.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>
Acked-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>