drm/msm: drop unused ring variable in msm_ioctl_gem_submit()

The variable ring is not used by msm_parse_deps() and
msm_ioctl_gem_submit() and thus can be dropped.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/529340/


Signed-off-by: Rob Clark <robdclark@chromium.org>