drm/msm: mdp4: drop vblank get/put from prepare/complete_commit

msm_atomic is doing vblank get/put's already,
currently there no need to duplicate the effort in MDP4

Fix warning:
...
WARNING: CPU: 3 PID: 79 at drivers/gpu/drm/drm_vblank.c:1194 drm_vblank_put+0x1cc/0x1d4
...
and multiple vblank time-outs:
...
msm 5100000.mdp: vblank time out, crtc=1
...

Tested on Nexus 7 2013 (deb), LTS 5.10.50.

Introduced by: 119ecb7f ("drm/msm/mdp4: request vblank during modeset")
Signed-off-by: David Heidelberg <david@ixit.cz>
Link: https://lore.kernel.org/r/20210715060925.7880-1-david@ixit.czSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c

@@ -89,13 +89,6 @@ static void mdp4_disable_commit(struct msm_kms *kms)
 
 static void mdp4_prepare_commit(struct msm_kms *kms, struct drm_atomic_state *state)
 {
-	int i;
-	struct drm_crtc *crtc;
-	struct drm_crtc_state *crtc_state;
-
-	/* see 119ecb7fd */
-	for_each_new_crtc_in_state(state, crtc, crtc_state, i)
-		drm_crtc_vblank_get(crtc);
 }
 
 static void mdp4_flush_commit(struct msm_kms *kms, unsigned crtc_mask)
@@ -114,12 +107,6 @@ static void mdp4_wait_flush(struct msm_kms *kms, unsigned crtc_mask)
 
 static void mdp4_complete_commit(struct msm_kms *kms, unsigned crtc_mask)
 {
-	struct mdp4_kms *mdp4_kms = to_mdp4_kms(to_mdp_kms(kms));
-	struct drm_crtc *crtc;
-
-	/* see 119ecb7fd */
-	for_each_crtc_mask(mdp4_kms->dev, crtc, crtc_mask)
-		drm_crtc_vblank_put(crtc);
 }
 
 static long mdp4_round_pixclk(struct msm_kms *kms, unsigned long rate,