Ports for intel e1000 and AMD pcnet ethernet chips available

[Till Straumann]

I recently ported the current 'em' driver from intel/Freebsd
which supports the 'e1000' chip family from intel
(82540..547, 82571..573, 82575, ICH8, ICH9 -- check source for details).

Also, I ported (and fixed) current Freebsd 'pcn' (Amd 79C971, 972, 973, 
975, 976, 978)
and 'le' [PCI only] drivers. 'le' is more generic than 'pcn', hence it 
supports older
chips as well.

In particular, the 'le' driver supports qemu's 79C970A emulation.

I have created a library and some ugly header files that mimic quite
a few things FreeBSD has but that are missing in the old RTEMS
bsdnet stack.

I have successfully tested

'em': mvme5500 board (powerpc, vme), concurrent-technologies PP410 (x86).
'pcn': mvme5500/6100 (powerpc), concurrent-technologies PP410 (x86).
'le': same as 'pcn' plus QEMU

I don't have time to package this up nicely so contact me
if you want any of these.

-- Till