drm/amd/pm: fix uninitialized variable warning

Check the return of function smum_send_msg_to_smc
as it may fail to initialize the variable.
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Tim Huang <Tim.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/powerplay/amd_powerplay.c

@@ -99,7 +99,7 @@ static void pp_swctf_delayed_work_handler(struct work_struct *work)
 	struct amdgpu_device *adev = hwmgr->adev;
 	struct amdgpu_dpm_thermal *range =
 				&adev->pm.dpm.thermal;
-	uint32_t gpu_temperature, size;
+	uint32_t gpu_temperature, size = sizeof(gpu_temperature);
 	int ret;
 
 	/*