Remove macros which aren't used anywhere in the driver, and which
conflict with macros of the same name used in the EFI headers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Suggested-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

Russ Nelson sent an email requesting the license change to
GPL Version 2.