bnxt_en: don't disable an already disabled PCI device

If device is already disabled in reset path and PCI io error is
detected before the device could be enabled, driver could
call pci_disable_device() for already disabled device. Fix this
problem by calling pci_disable_device() only if the device is already
enabled.

Fixes: 6316ea6d ("bnxt_en: Enable AER support.")
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -13436,6 +13436,7 @@ static pci_ers_result_t bnxt_io_error_detected(struct pci_dev *pdev,
 	if (netif_running(netdev))
 		bnxt_close(netdev);
 
+	if (pci_is_enabled(pdev))
 		pci_disable_device(pdev);
 	bnxt_free_ctx_mem(bp);
 	kfree(bp->ctx);