media: atomisp: Remove unused atomisp_buffers_queued[_pipe] functions

The atomisp_buffers_queued[_pipe] functions are not used anywhere,
remove them.

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