More driver status information regarding use of busdma to abstract
dma access:

if_mn Nope
if_pcn Nope
if_sf Nope
if_sk Nope
if_ste Nope
if_tl Nope
if_vr Nope
if_wb Nope
amd Nope (Is this OK due to CAM?)
ncr Nope (Is this OK due to CAM?)
meteor Nope

Also: the simos.c driver uses vtophys(), but is documented as being
broken, so isn't listed.