PCI: tegra: Fix return value check of pm_runtime_get_sync()

pm_runtime_get_sync() returns the device's usage counter. This might
be >0 if the device is already powered up or CONFIG_PM is disabled.

Abort probe function on real error only.

Fixes: da76ba50 ("PCI: tegra: Add power management support")
Link: https://lore.kernel.org/r/20191216111825.28136-1-david.engraf@sysgo.comSigned-off-by: David Engraf <david.engraf@sysgo.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Andrew Murray <andrew.murray@arm.com>
Cc: stable@vger.kernel.org	# v4.17+

drivers/pci/controller/pci-tegra.c

@@ -2798,7 +2798,7 @@ static int tegra_pcie_probe(struct platform_device *pdev)
 
 	pm_runtime_enable(pcie->dev);
 	err = pm_runtime_get_sync(pcie->dev);
-	if (err) {
+	if (err < 0) {
 		dev_err(dev, "fail to enable pcie controller: %d\n", err);
 		goto teardown_msi;
 	}