net: libwx: Add irq flow functions

Add irq flow functions for ngbe and txgbe.
Alloc pcie msix irqs for drivers, otherwise fall back to msi/legacy.

Signed-off-by: Mengyuan Lou <mengyuanlou@net-swift.com>
Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>