media: atomisp: Drop atomisp_is_vf_pipe()

Since there only is one /dev/video# node now (no more continuous mode),
there are now no longer separate main capture + view-finder pipes.

We are now always on the main pipe, so atomisp_is_vf_pipe() should
always return false now. Drop any checks using it, replacing them
with the code-path for a false return.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>