sweeping change over all NIC drivers

  Hi,

I'd like to commit a sweeping change over all NIC drivers,
details can be found here:

https://reviews.freebsd.org/D21943

The stack changes froim the review are already committed,
only a bunch of drivers are left. You can browse them as
individual commits here:

https://github.com/glebius/FreeBSD/commits/if_foreach_maddr

Although changes are close to trivial, there is always a place
for a mistake. So reviewing is appreciated. Testing is even
more appreciated. Here is list of drivers affected (65 total):

xl
xae
wi
vtnet
vte
vr
vmxnet3
vge
tsec
ti
stge
ste
sk
sis
sge
rtwn
rl
re
qlxge
qlxgbe
qlxgb
qlnx
ps3
otus
oce
nge
nfe
ndis
my
msk
mge
malo
llan
lio
lge
le
jme
hme
gem
fxp
fv
ffec
et
emac
em
dwc
dc
cxgbe
cxgb
cpsw
cgem
cas
bxe
bnxt
bge
bfe
bce
awg
atse
ath
ale
alc
al_eth
age
ae

-- 
Gleb Smirnoff