[hermon] Add support for ConnectX-3 based cards

[hermon] Add support for ConnectX-3 based cards

After a ton of tedious work, I am pleased to finally introduce full
support for ConnectX-3 cards in iPXE!

The work has been done by finding all publicly available versions of
the Mellanox Flexboot sources, cleaning them up, synthesizing a git
history from them, cleaning out non-significant changes, and
correlating with the iPXE upstream git history.

After this, a proof-of-concept diff was produced, that allowed iPXE to
be compiled with rudimentary ConnectX-3 support. This diff was over
10k lines, and contained many changes that were not part of the core
driver.

Special thanks to Michael Brown <mcb30@ipxe.org> for answering my
barrage of questions, and helping brainstorm the development along the
way.

Signed-off-by: Christian Iversen <ci@iversenit.dk>