Add initial BCM5718 family support. The BCM5718 family includes

Add initial BCM5718 family support. The BCM5718 family includes
the dual port BCM5717 and BCM5718 devices which are intended for
mainstream workstation and entry-level server designs and
represents the twelfth generation of NetXtreme Ethernet controllers.
This family is the successor to the BCM5714/BCM5715 family and
supports IPv4/IPv6 checksum offloading, TSO, VLAN hardware tagging,
jumbo frames, MSI/MSIX, IOV, RSS and TSS.

This change set supports all hardware features except IOV and
RSS/TSS. Unlike its predecessors, only extended RX buffer
descriptors can be posted to the jumbo producer ring. Single RX
buffer descriptors for jumbo frame are not supported. RSS requires
a more substantial set of changes and will apply to a larger set
of NetXtreme devices so RSS/TSS multi-queue support will be
implemented in a future releases.

Special thanks to Broadcom who kindly sent a sample board to me
and to davidch who gave provided the initial support code.

Submitted by:	davidch (initial version)
HW donated by:	Broadcom