It's the responsibility of a correctly written DRM modeset driver to
call drm_atomic_helper_shutdown() at shutdown time and that should be
disabling / unpreparing the panel if needed. Panel drivers shouldn't
be calling these functions themselves.

A recent effort was made to fix as many DRM modeset drivers as
possible [1] [2] [3] and most drivers are fixed now.

A grep through mainline for compatible strings used by this driver
indicates that it is used by Rockchip boards. The Rockchip driver
appears to be correctly calling drm_atomic_helper_shutdown() so we can
remove the calls.

[1] https://lore.kernel.org/r/20230901234015.566018-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[3] https://lore.kernel.org/r/20230921192749.1542462-1-dianders@chromium.org

Cc: Chris Zhong <zyw@rock-chips.com>
Cc: Lin Huang <hl@rock-chips.com>
Cc: Brian Norris <briannorris@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.9.Iaddb8e0cab570e2f8066a4baf1d49239a820b799@changeid