drm/scheduler: fix sched_fence.c kernel-doc warnings

Fix kernel-doc warnings.
drivers/gpu/drm/scheduler/sched_fence.c:110: warning: Function parameter or
member 'f' not described in 'drm_sched_fence_release_scheduled'
drivers/gpu/drm/scheduler/sched_fence.c:110: warning: Excess function
parameter 'fence' description in 'drm_sched_fence_release_scheduled'

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>