drm/amd/amdgpu: remove defined but not used 'crtc_offsets'

Fix the following gcc warning:

drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c:65:18: warning: ‘crtc_offsets’
defined but not used [-Wunused-const-variable=]
 static const u32 crtc_offsets[6] =
                  ^~~~~~~~~~~~
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c

@@ -61,17 +61,6 @@ MODULE_FIRMWARE("amdgpu/si58_mc.bin");
 #define MC_SEQ_MISC0__MT__HBM    0x60000000
 #define MC_SEQ_MISC0__MT__DDR3   0xB0000000
 
-
-static const u32 crtc_offsets[6] =
-{
-	SI_CRTC0_REGISTER_OFFSET,
-	SI_CRTC1_REGISTER_OFFSET,
-	SI_CRTC2_REGISTER_OFFSET,
-	SI_CRTC3_REGISTER_OFFSET,
-	SI_CRTC4_REGISTER_OFFSET,
-	SI_CRTC5_REGISTER_OFFSET
-};
-
 static void gmc_v6_0_mc_stop(struct amdgpu_device *adev)
 {
 	u32 blackout;