These haven't been used since the driver was upstreamed in 2013.

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

 drivers/gpu/drm/radeon/kv_dpm.c:161:40: warning: ‘cpl_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:156:40: warning: ‘mc3_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:151:40: warning: ‘mc2_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:146:40: warning: ‘mc1_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:141:40: warning: ‘mc0_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:136:40: warning: ‘sx0_cac_config_reg’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:104:43: warning: ‘cpl_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:98:43: warning: ‘mc3_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:92:43: warning: ‘mc2_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:86:43: warning: ‘mc1_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:80:43: warning: ‘mc0_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/radeon/kv_dpm.c:67:43: warning: ‘sx_local_cac_cfg_kv’ defined but not used [-Wunused-const-variable=]

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>