drm/format-helper: Add drm_fb_xrgb8888_to_rgb888()

commit 7b501ae10a0132e38ff2d61a432fa4143b3a8df3 from
https://nv-tegra.nvidia.com/r/3rdparty/canonical/linux-jammy.git

 jetson_36.3

Add XRGB8888 emulation support for devices that can only do RGB888.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210929191201.34456-4-noralf@tronnes.org


(cherry picked from commit bcf80d6e)
Change-Id: I395f119ccffe78c3a94fea4d6c341532dd26cf47
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/3rdparty/canonical/linux-jammy/+/2985819


Reviewed-by: svcacv <svcacv@nvidia.com>
Reviewed-by: Jonathan Hunter <jonathanh@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
Signed-off-by: Rajeshkumar Ramasamy <rajeshkumar.ramasamy@windriver.com>