drm/msm/dpu: clean up some inconsistent indenting

Eliminate the follow smatch warning:
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c:411
_dpu_crtc_blend_setup_mixer() warn: inconsistent indenting

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Link: https://lore.kernel.org/r/20220208012321.43587-1-yang.lee@linux.alibaba.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>