wil6210: fix access after free in wil_pcie_remove()

'wil'  released in wil_if_free(); save iomapped address aside to
properly unmap it.
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/wil6210/pcie_bus.c

@@ -218,12 +218,13 @@ static int wil_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 static void wil_pcie_remove(struct pci_dev *pdev)
 {
 	struct wil6210_priv *wil = pci_get_drvdata(pdev);
+	void __iomem *csr = wil->csr;
 
 	wil6210_debugfs_remove(wil);
 	wil_if_pcie_disable(wil);
 	wil_if_remove(wil);
 	wil_if_free(wil);
-	pci_iounmap(pdev, wil->csr);
+	pci_iounmap(pdev, csr);
 	pci_release_region(pdev, 0);
 	pci_disable_device(pdev);
 }