media: atomisp: Make it possible to call atomisp_set_fmt() without a file handle

To fix atomisp_queue_setup() sometimes failing it needs to be able to call
atomisp_set_fmt(), but atomisp_queue_setup() (VIDIOC_REQBUFS) does not get
passed a file handle by the videobuf2 core.

Partly revert commit b3be98f984d4 ("media: atomisp: Remove a couple of not
useful function wrappers") so that atomisp_set_fmt() can be used
without a file handle.

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>