drm/msm: small fence cleanup

Give ourselves a way to wait for certain fence #..  makes it easier to
wait on a set of bo's, which we'll need for atomic.

Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --cc drivers/gpu/drm/msm/msm_drv.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_drv.h
Simple merge

diff --cc drivers/gpu/drm/msm/msm_gem.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_gem.h
Simple merge