drm/amdgpu: Fix inconsistent of format with argument type in amdgpu_xgmi.c

Fix follow warning:
[drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c:249]: (warning) %d in format
string (no. 1) requires 'int' but the argument type is 'unsigned int'.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -246,7 +246,7 @@ static ssize_t amdgpu_xgmi_show_error(struct device *dev,
 
 	adev->df.funcs->set_fica(adev, ficaa_pie_status_in, 0, 0);
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", error_count);
+	return snprintf(buf, PAGE_SIZE, "%u\n", error_count);
 }