glamor: Use gbm_bo_create_with_modifiers for internal pixmap allocation

Using modifier might allow the driver to use a more optimal format
(e.g. tiled/compressed). Let's try to use those if possible.

v2: Don't filter out multi-plane modifiers

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>