thermal/drivers/int340x/processor_thermal: Fix warning for return value

Fix smatch warnings:
drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c:258 proc_thermal_pci_probe() warn: missing error code 'ret'

Use PTR_ERR to return failure of thermal_zone_device_register().
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210628183232.62877-1-srinivas.pandruvada@linux.intel.com

drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c

@@ -254,8 +254,10 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
 	pci_info->tzone = thermal_zone_device_register("TCPU_PCI", 1, 1, pci_info,
 							&tzone_ops,
 							&tzone_params, 0, 0);
-	if (IS_ERR(pci_info->tzone))
+	if (IS_ERR(pci_info->tzone)) {
+		ret = PTR_ERR(pci_info->tzone);
 		goto err_ret_mmio;
+	}
 
 	/* request and enable interrupt */
 	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);