drm/amdgpu: return early on error while setting bar0 memtype

We set WC memtype for aper_base but don't check return value
of arch_io_reserve_memtype_wc(). Be more defensive and return
early on error.
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1032,9 +1032,14 @@ int amdgpu_bo_init(struct amdgpu_device *adev)
 	/* On A+A platform, VRAM can be mapped as WB */
 	if (!adev->gmc.xgmi.connected_to_cpu) {
 		/* reserve PAT memory space to WC for VRAM */
-		arch_io_reserve_memtype_wc(adev->gmc.aper_base,
+		int r = arch_io_reserve_memtype_wc(adev->gmc.aper_base,
 				adev->gmc.aper_size);
 
+		if (r) {
+			DRM_ERROR("Unable to set WC memtype for the aperture base\n");
+			return r;
+		}
+
 		/* Add an MTRR for the VRAM */
 		adev->gmc.vram_mtrr = arch_phys_wc_add(adev->gmc.aper_base,
 				adev->gmc.aper_size);