drm/msm/mdp5: Eliminate useless code

Since mdp5_state is initialized twice at the same time, so
we make code simple and easy to understand by delete one.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/482500/
Link: https://lore.kernel.org/r/1650348980-19050-1-git-send-email-baihaowen@meizu.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c

@@ -382,8 +382,6 @@ static int mdp5_plane_atomic_async_check(struct drm_plane *plane,
 	if (!crtc_state->active)
 		return -EINVAL;
 
-	mdp5_state = to_mdp5_plane_state(new_plane_state);
-
 	/* don't use fast path if we don't have a hwpipe allocated yet */
 	if (!mdp5_state->hwpipe)
 		return -EINVAL;