Tie into existing driver API; we'll fix that up soon.

even when __atribute__ (( unused )) is correctly set...

I want to get to the point where any header in include/ reflects a
standard user-level header (e.g. a POSIX header), while everything that's
specific to gPXE lives in include/gpxe/.  Headers that reflect a Linux
header (e.g. if_ether.h) should also be in include/gpxe/, with the same
name as the Linux header and, preferably, the same names used for the
definitions.

implementation allows for only one, and does so without compromising on
the efficiency of static allocation).

Link-layer protocols are cleanly separated from the device drivers.

Network-layer protocols are cleanly separated from individual network
devices.

Link-layer and network-layer protocols are cleanly separated from each
other.

No code changes apart from commenting one unused function out.

symbol.

Moved transmit before poll, since typically transmit will be implemented first.

Use shared symbols.
Correct other symbol violations.

thinks they are.
Other bus drivers modified for consistency.

perl -pi -0777 -e 's/^static struct \w+_driver (\w+) =\s*(\w+_DRIVER \()/${2} ${1},/msg' *.c