drm/sysfb: Generalize pixel-format matching

drm/sysfb: Generalize pixel-format matching

Provide drm_sysfb_get_format(), a helper that finds a specific DRM
format from a list of pixel formats. The new function builds upon
drm_sysfb_get_format_si(), which finds the DRM format from a given
instance of struct screen_info. Now get the screen_info's pixel format
in the caller. Allows for matching pixel formats in drivers without
screen_info.

Convert the callers in efidrm and vesadrm to the new interface.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Julius Werner <jwerner@chromium.org>
Link: https://patch.msgid.link/20260217155836.96267-11-tzimmermann@suse.de