drm/msm: fix _NO_IMPLICIT fencing case

We need to call reservation_object_reserve_shared() in both cases, but
this wasn't happening in the _NO_IMPLICIT submit case.

Fixes: f0a42bb5 ("drm/msm: submit support for in-fences")
Reported-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>