media: atomisp: Remove a couple of not useful function wrappers

The __atomisp_reqbufs(), __atomisp_streamoff() are 1:1 wrappers for
the non __ prefixed functions now, drop these wrappers.

The atomisp_s_fmt_cap() wrapper is almost a 1:1 wrapper for
atomisp_set_fmt() adjust the latter to have the right function
prototype and drop the wrapper.

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