To obtain detachable flag, pci_drv is accessed in rte_eth_dev_is_detachable().
But pci_drv is only valid if port is enabled. Not to cause illegal access,
add rte_eth_dev_is_valid_port() before accessing.
Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>