thermal: int340x_thermal: Fix a NULL vs IS_ERR() check

The intel_soc_dts_iosf_init() function doesn't return NULL, it returns
error pointers.

Fixes: 4d0dd6c1 ("Thermal/int340x/processor_thermal: Enable auxiliary DTS for Braswell")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/intel/int340x_thermal/processor_thermal_device.c

@@ -423,7 +423,7 @@ static int  proc_thermal_pci_probe(struct pci_dev *pdev,
 		proc_priv->soc_dts = intel_soc_dts_iosf_init(
 					INTEL_SOC_DTS_INTERRUPT_MSI, 2, 0);
 
-		if (proc_priv->soc_dts && pdev->irq) {
+		if (!IS_ERR(proc_priv->soc_dts) && pdev->irq) {
 			ret = pci_enable_msi(pdev);
 			if (!ret) {
 				ret = request_threaded_irq(pdev->irq, NULL,