drm/sysfb: Share helpers for screen_info validation

drm/sysfb: Share helpers for screen_info validation

Share efidrm's and vesadrm's validation of struct screen_info in
shared helpers. Update the drivers.

Most validation helpers test individual values against limits and
can be shared as they are. For color formats, a common helper looks
up the correct DRM format info from a driver-provided list of color
formats.

These screen_info helpers are only available if CONFIG_SCREEN_INFO
has been selected, as done by efidrm and vesadrm.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250410083834.10810-4-tzimmermann@suse.de