drm/amd/amdgpu/uvd_v4_2: Add one and remove another function param description

drm/amd/amdgpu/uvd_v4_2: Add one and remove another function param description

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c:448: warning: Function parameter or member 'flags' not described in 'uvd_v4_2_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c:448: warning: Excess function parameter 'fence' description in 'uvd_v4_2_ring_emit_fence'

Acked-by: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>