drm/msm: remove variable set but not used

The code that uses variable mdss has been removed, So the declaration
and assignment of the variable can be removed.

Eliminate the following clang warning:
drivers/gpu/drm/msm/msm_drv.c:513:19: warning: variable 'mdss' set but
not used [-Wunused-but-set-variable]

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Fixes: 2027e5b341 ("drm/msm: Initialize MDSS irq domain at probe time")
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20211216031103.34146-1-yang.lee@linux.alibaba.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/msm_drv.c

@@ -510,7 +510,6 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
 	struct msm_drm_private *priv = dev_get_drvdata(dev);
 	struct drm_device *ddev;
 	struct msm_kms *kms;
-	struct msm_mdss *mdss;
 	int ret, i;
 
 	ddev = drm_dev_alloc(drv, dev);
@@ -521,8 +520,6 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
 	ddev->dev_private = priv;
 	priv->dev = ddev;
 
-	mdss = priv->mdss;
-
 	priv->wq = alloc_ordered_workqueue("msm", 0);
 	priv->hangcheck_period = DRM_MSM_HANGCHECK_DEFAULT_PERIOD;