Replace the inner loop of drm_fb_swab() with helper functions that
swap the bytes in each pixel. This will allow to share the outer
loop with other conversion helpers.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220427141409.22842-2-tzimmermann@suse.de