drm/radeon/r600_cs: Fix some doc-rot and supply missing function param docs

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

 drivers/gpu/drm/radeon/r600_cs.c:793: warning: Function parameter or member 'p' not described in 'r600_cs_packet_parse_vline'
 drivers/gpu/drm/radeon/r600_cs.c:793: warning: Excess function parameter 'parser' description in 'r600_cs_packet_parse_vline'
 drivers/gpu/drm/radeon/r600_cs.c:826: warning: Function parameter or member 'p' not described in 'r600_cs_common_vline_parse'
 drivers/gpu/drm/radeon/r600_cs.c:826: warning: Excess function parameter 'parser' description in 'r600_cs_common_vline_parse'
 drivers/gpu/drm/radeon/r600_cs.c:968: warning: Function parameter or member 'p' not described in 'r600_cs_check_reg'
 drivers/gpu/drm/radeon/r600_cs.c:968: warning: Excess function parameter 'parser' description in 'r600_cs_check_reg'
 drivers/gpu/drm/radeon/r600_cs.c:1473: warning: Function parameter or member 'base_offset' not described in 'r600_check_texture_resource'
 drivers/gpu/drm/radeon/r600_cs.c:1473: warning: Function parameter or member 'mip_offset' not described in 'r600_check_texture_resource'
 drivers/gpu/drm/radeon/r600_cs.c:1473: warning: Function parameter or member 'tiling_flags' not described in 'r600_check_texture_resource'

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>