Add -D option to add the drivername and unit number to ifconfig output
for normal display, including -a. Use ifconfig_get_orig_name() from
libifconfig to fetch the name. Note that this is the original name
for most drivers, but not for some exceptions like epair (which appends
'a' or 'b' to the unit number). epair interface pairs both display
as "epair0", etc.