drm/msm/dp: Remove unused variable

drm/msm/dp: Remove unused variable

Kernel test roobot throws below warning ->

drivers/gpu/drm/msm/dp/dp_display.c:1017:21:
warning: variable 'drm' set but not used [-Wunused-but-set-variable]

Removed unused variable drm.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Link: https://lore.kernel.org/r/20210709024834.29680-1-jrdr.linux@gmail.com
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>