Merge tag 'drm-msm-fixes-2020-09-04' of https://gitlab.freedesktop.org/drm/msm into drm-fixes

A few fixes for a potential RPTR corruption issue.

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CAF6AEGvnr6Nhz2J0sjv2G+j7iceVtaDiJDT8T88uW6jiBfOGKQ@mail.gmail.com