drm/amdgpu: remove set but not used variable 'mc_shared_chmap' from 'gfx_v6_0.c' and 'gfx_v7_0.c'

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

drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c: In function
‘gfx_v6_0_constants_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c:1579:6: warning: variable
‘mc_shared_chmap’ set but not used [-Wunused-but-set-variable]

drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c: In function
‘gfx_v7_0_gpu_early_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c:4262:6: warning: variable
‘mc_shared_chmap’ set but not used [-Wunused-but-set-variable]

Fixes: 2cd46ad22383 ("drm/amdgpu: add graphic pipeline implementation for si v8")
Fixes: d93f3ca706b8 ("drm/amdgpu/gfx7: rework gpu_init()")
Signed-off-by: yu kuai <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c

···
 static void gfx_v6_0_constants_init(struct amdgpu_device *adev)
 {
 	u32 gb_addr_config = 0;
-	u32 mc_shared_chmap, mc_arb_ramcfg;
+	u32 mc_arb_ramcfg;
 	u32 sx_debug_1;
 	u32 hdp_host_path_cntl;
 	u32 tmp;
···
 
 	WREG32(mmBIF_FB_EN, BIF_FB_EN__FB_READ_EN_MASK | BIF_FB_EN__FB_WRITE_EN_MASK);
 
-	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;
 

drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c

···
 static void gfx_v7_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;
 
···
 		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;