drm/sysfb: Remove duplicate declarations

drm/sysfb: Remove duplicate declarations

Commit 6046b49bafff ("drm/sysfb: Share helpers for integer validation")
and commit e8c086880b2b ("drm/sysfb: Share helpers for screen_info
validation") added duplicate function declarations. Remove the latter
ones.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: e8c086880b2b ("drm/sysfb: Share helpers for screen_info validation")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.16+
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patch.msgid.link/20260108145058.56943-7-tzimmermann@suse.de