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: 2027e5b3 ("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.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>