Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Backport just the sys/{dev,modules}/cxgb{,e}/ parts of r237263, and then
disable the TOE and iWARP modules in the Makefiles (they won't compile
without the rest of r237263).

This reduces diffs between the cxgb/cxgbe drivers in head and 9 and
makes it easy to MFC other fixes to 9.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

import support for iwarp on Chelsio T3 card

Supported by Chelsio Inc.