device: add support for configuring bonding devices

device: add support for configuring bonding devices

Supported options:

- ports: member devices
- policy: bonding policy
	supported values:
	- balance-rr
	- active-backup
	- balance-xor
	- broadcast
	- 802.3ad
	- balance-tlb
	- balance-alb
- xmit_hash_policy: slave selection tx hash policy
	supported values:
	- layer2
	- layer2+3
	- layer3+4
	- encap2+3
	- encap3+4
- all_ports_active: allow receiving on inactive ports
- min_links: minimum number of active links
- ad_actor_system: LACPDU exchange MAC address
- ad_actor_sys_prio: LACPDU priority value
- ad_select: 802.3ad aggregation logic
	supported values:
	- stable
	- bandwidth
	- count
- lacp_rate: 802.3ad LACPDU packet rate
	supported values:
	- slow (every 30 seconds)
	- fast (every second)
- packets_per_port: number of packets before switching
  ports (balance-rr mode).
- lp_interval: number of seconds between sent learning packets
- dynamic_lb: distribute traffic according to port load
- resend_igmp: number if IGMP membership updates after failover event
- num_peer_notif: number of tx unsolicited ARP/NA after failover event
- primary: name of the primary port
- primary_reselect: primary port reselection policy
	supported values:
	- always
	- better
	- failure
- failover_mac: MAC address selection policy
	supported values:
	- none
	- active
	- follow
- monitor_mode: select ARP or MII link monitor:
	supported values:
	- arp
	- mii
- monitor_interval: link monitor update interval (msec)
- arp_target: ARP monitor target IP address (list)
- arp_all_targets: all targets must be reachable to consider the link valid
- arp_validate: ARP validation policy
	supported values:
	- none
	- active
	- backup
	- all
	- filter
	- filter_active
	- filter_backup
- use_carrier: use carrier status instead of MII ioctl result
- updelay: delay before enabling port after MII link up event (msec)
- downdelay: delay before disabling port after MII link down event (msec)

Signed-off-by: Felix Fietkau <nbd@nbd.name>