drm/msm: args->fence should be args->flags

Fix a typo in msm_ioctl_gem_submit - check args->flags for the
MSM_SUBMIT_NO_IMPLICIT flag instead of args->fence.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>