xhci: tegra: Prevent error pointer dereference

During initialization, the host and super-speed power domains will
contain an ERR_PTR() encoded error code rather than being NULL. To
avoid a crash, use a !IS_ERR_OR_NULL() condition during cleanup.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Fixes: 6494a9ad ("usb: xhci: tegra: Add genpd support")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-tegra.c

@@ -941,9 +941,9 @@ static void tegra_xusb_powerdomain_remove(struct device *dev,
 		device_link_del(tegra->genpd_dl_ss);
 	if (tegra->genpd_dl_host)
 		device_link_del(tegra->genpd_dl_host);
-	if (tegra->genpd_dev_ss)
+	if (!IS_ERR_OR_NULL(tegra->genpd_dev_ss))
 		dev_pm_domain_detach(tegra->genpd_dev_ss, true);
-	if (tegra->genpd_dev_host)
+	if (!IS_ERR_OR_NULL(tegra->genpd_dev_host))
 		dev_pm_domain_detach(tegra->genpd_dev_host, true);
 }