drm/ast: Rename support_wide_screen to support_wsxga_p

The flag support_wide_screen in struct ast_device selects devices that
support resolutions of at least 1680x1050 (WSXGA+). Name it accordingly.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250131092257.115596-4-tzimmermann@suse.de