drm/stm: Don't set allow_fb_modifiers explicitly

drm/stm: 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.

Acked-by: Philippe Cornu <philippe.cornu@st.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Yannick Fertre <yannick.fertre@foss.st.com>
Cc: Philippe Cornu <philippe.cornu@foss.st.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-arm-kernel@lists.infradead.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210427092018.832258-7-daniel.vetter@ffwll.ch