cmds/ip: add ip link set (hardware) address
cmds/ip: add ip link set (hardware) address

Provide the ability for u-root to modify the hardware (mac) address.

Follows the same structure as other 'ip link set' commands.

usage:
~/> ip link set eth1 address 00:00:00:02:01:01

results:
~/> ip link show
3: eth1: <UP,BROADCAST,MULTICAST> mtu 1500 state UP
    link/ether 00:00:00:00:00:01

error reporting:
~/> ip link set eth1 address 00:00:00:02:01:0h
ip: &{{3 1500 1000 eth1 00:00:00:02:01:01 up|broadcast|multicast
69699 0 0 <nil>  0xc42017c0e4 0 0xc420016680 ether <nil> up 0 0 0}}
cant parse mac addr : address 00:00:00:02:01:0h: invalid MAC address

GanShun/u-root,rminnich/u-root,rminnich/u-root,GanShun/u-root,hugelgupf/u-root,rminnich/u-root,hugelgupf/u-root,u-root/u-root,rminnich/u-root,u-root/u-root,u-root/u-root,GanShun/u-root,hugelgupf/u-root,hugelgupf/u-root