media: atomisp: Remove atomisp_css_yuvpp_configure_viewfinder() function

Remove atomisp_css_yuvpp_configure_viewfinder(), it is not used anywhere.

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>