[efi] Include NII driver within "snp" and "snponly" build targets
End users almost certainly don't care whether the underlying interface
is SNP or NII/UNDI. Try to minimise surprise and unnecessary
documentation by including the NII driver whenever the SNP driver is
requested.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Rewrite the SNP NIC driver to use non-blocking and deferrable
transmissions, to provide link status detection, to provide
information about the underlying (PCI) hardware device, and to avoid
unnecessary I/O buffer allocations during receive polling.
Signed-off-by: Michael Brown <mcb30@ipxe.org>