nve: ethernet address reversal code

[Danny Braniss]

I compiled the latest -current, with the latest nfe, and I got a slight 
regression :-)
...
nfe0: <NVIDIA nForce 430 MCP12 Networking Adapter> port 0xdc00-0xdc07 mem 
0xfe02c000-0xfe02cfff irq 21 at device 20.0 on pci0
nfe0: Ethernet address: 50:71:a9:f3:18:00
nfe0: MII without any phy!
kernel trap 12 with interrupts disabled


Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x1b8
fault code              = supervisor read data, page not present
instruction pointer     = 0x8:0xffffffff80448cdf
stack pointer           = 0x10:0xffffffff80aea7a0
frame pointer           = 0x10:0xffffffff80aea7d0
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = resume, IOPL = 0
current process         = 0 (swapper)
[thread pid 0 tid 0 ]
Stopped at      _mtx_lock_sleep+0x7f:   movl    0x1b8(%r13),%r9d

with a slightly older nfe:

nfe0: <NVIDIA nForce 430 MCP12 Networking Adapter> port 0xdc00-0xdc07 mem 
0xfe02c000-0xfe02cfff irq 21 at device 20.0 on pci0
nfe0: Ethernet address: 50:71:a9:f3:18:00
miibus1: <MII bus> on nfe0
e1000phy0: <Marvell 88E1111 Gigabit PHY> PHY 11 on miibus1
e1000phy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseTX-FDX, 
auto

danny