drm/doc: Fix comment typo

drm/doc: Fix comment typo

Replace apprpriately with appropriately.

Fixes: 5d90341ef6522 ("drm/doc: Polish plane composition property docs")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Simon Ser <contact@emersion.fr>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/20220628003407.77765-1-marex@denx.de