drivers/net: fix device configuration

drivers/net: fix device configuration

dev_flags is wrongly overwritten with RTE_ETH_DEV_DETACHABLE value
in drivers after rte_eth_copy_pci_info().

Previous values of the dev_flags set in rte_eth_copy_pci_info(),
like RTE_ETH_DEV_INTR_LSC, are get lost. That will fail the device
configuration.

Fix by preventing dev_flags overwritten.

Fixes: 22dda618c00c ("pci: separate detaching ethernet ports from PCI devices")
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Signed-off-by: Jeff Guo <jia.guo@intel.com>