media: atomisp: Add ia_css_frame_pad_width() helper function

Factor the code to go from width to a properly aligned pitch out of
ia_css_frame_info_set_width().

This is a preparation patch to fix try_fmt() calls returning a bogus
bytesperline value.

Link: https://lore.kernel.org/r/20230529103741.11904-14-hdegoede@redhat.com



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