drm/amd/amdgpu/vcn_v2_0: Fix a few kernel-doc misdemeanours

drm/amd/amdgpu/vcn_v2_0: Fix a few kernel-doc misdemeanours

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

 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:483: warning: Excess function parameter 'sw' description in 'vcn_v2_0_disable_clock_gating'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:644: warning: Excess function parameter 'sw' description in 'vcn_v2_0_enable_clock_gating'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1404: warning: Function parameter or member 'count' not described in 'vcn_v2_0_dec_ring_insert_nop'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1426: warning: Function parameter or member 'addr' not described in 'vcn_v2_0_dec_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1426: warning: Function parameter or member 'seq' not described in 'vcn_v2_0_dec_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1426: warning: Function parameter or member 'flags' not described in 'vcn_v2_0_dec_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1426: warning: Excess function parameter 'fence' description in 'vcn_v2_0_dec_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1465: warning: Function parameter or member 'job' not described in 'vcn_v2_0_dec_ring_emit_ib'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1465: warning: Function parameter or member 'flags' not described in 'vcn_v2_0_dec_ring_emit_ib'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1609: warning: Function parameter or member 'addr' not described in 'vcn_v2_0_enc_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1609: warning: Function parameter or member 'seq' not described in 'vcn_v2_0_enc_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1609: warning: Function parameter or member 'flags' not described in 'vcn_v2_0_enc_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1609: warning: Excess function parameter 'fence' description in 'vcn_v2_0_enc_ring_emit_fence'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1636: warning: Function parameter or member 'job' not described in 'vcn_v2_0_enc_ring_emit_ib'
 drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1636: warning: Function parameter or member 'flags' not described in 'vcn_v2_0_enc_ring_emit_ib'

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>