drm/nouveau: Don't set allow_fb_modifiers explicitly

drm/nouveau: Don't set allow_fb_modifiers explicitly

Since

commit c1ab5d547a8ee6672763716402fcfb28545c7a16
Author: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Date:   Fri Jan 4 09:56:10 2019 +0100

    drm: Auto-set allow_fb_modifiers when given modifiers at plane init

this is done automatically as part of plane init, if drivers set the
modifier list correctly. Which is the case here.

Note that this fixes an inconsistency: We've set the cap everywhere,
but only nv50+ supports modifiers. Hence cc stable, but not further
back then the patch from Paul.

Reviewed-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org # v5.1 +
Cc: Pekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: nouveau@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210427092018.832258-6-daniel.vetter@ffwll.ch