drm/amdgpu: remove set but not used variable 'mc_shared_chmap'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c: In function
‘gfx_v8_0_gpu_early_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c:1713:6: warning: variable
‘mc_shared_chmap’ set but not used [-Wunused-but-set-variable]

Fixes: 0bde3a95 ("drm/amdgpu: split gfx8 gpu init into sw and hw parts")
Signed-off-by: yu kuai <yukuai3@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -1710,7 +1710,7 @@ static int gfx_v8_0_do_edc_gpr_workarounds(struct amdgpu_device *adev)
 static int gfx_v8_0_gpu_early_init(struct amdgpu_device *adev)
 {
 	u32 gb_addr_config;
-	u32 mc_shared_chmap, mc_arb_ramcfg;
+	u32 mc_arb_ramcfg;
 	u32 dimm00_addr_map, dimm01_addr_map, dimm10_addr_map, dimm11_addr_map;
 	u32 tmp;
 	int ret;
@@ -1850,7 +1850,6 @@ static int gfx_v8_0_gpu_early_init(struct amdgpu_device *adev)
 		break;
 	}
 
-	mc_shared_chmap = RREG32(mmMC_SHARED_CHMAP);
 	adev->gfx.config.mc_arb_ramcfg = RREG32(mmMC_ARB_RAMCFG);
 	mc_arb_ramcfg = adev->gfx.config.mc_arb_ramcfg;