drm/msm/a6xx: Add missing suspend_count increment

Reported-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Fixes: 3ab1c5cc

 ("drm/msm: Add param for userspace to query suspend count")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220113163215.215367-1-robdclark@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>