drm/msm/mdp4: Fix modifier support enabling

Setting the cap without the modifier list is very confusing to
userspace. Fix that by listing the ones we support explicitly.

Stable backport so that userspace can rely on this working in a
reasonable way, i.e. that the cap set implies IN_FORMATS is available.

Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Pekka Paalanen <pekka.paalanen@collabora.com>
Cc: Rob Clark <robdclark@chromium.org>
Cc: Jordan Crouse <jordan@cosmicpenguin.net>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210427092018.832258-5-daniel.vetter@ffwll.ch