Multi-NIC support

[IanSeyler]

These changes are in the multi-net branch.

At the moment BareMetal only supports a single NIC. There are use cases where multiple network connections may be required.

TODO:

• Add RDX as a parameter for Device to b_net_rx and b_net_tx
• Move bus_table into system variables memory
• Increase os_net_mem memory to 192K (64K rx, 64K tx, 64K packet buffers)
• init_net - Find all network devices, keep a count, find supported network devices, divide available memory for tx/rx ring buffers, init each device
• Each driver init should use os_net_icount when storing device details to the table
• Each driver should pull their values from the network device table. Also, the respective _reset, _transmit, _poll need to accept RDX for interface
• Keep an indexable table of enabled network devices - qwords netIOBase, transmit, poll, stats, rx tail, tx tail
• b_net_status return MAC of Interface, 0 if Interface invalid
• i8254x
• i8257x
• i8259x
• virtio
• rtl8169

First step will be the network device table. The existing drivers will need to be adjusted to support that table.