MFC r203945:

MFC r203945:
  adds bwn(4) driver for supporting Broadcom BCM43xx chipsets.

    o uses v4 firmware instead of v3.  A port will be committed to
      create the bwn firmware module.
    o supports B/G and LP(low power) PHYs.
    o supports 32 / 64 bits DMA operations.
    o tested on big / little endian machines so should work on all
      architectures.

  It'd not connected to the build until the firmware port is committed.

git-svn-id: svn://svn.freebsd.org/base/stable/8@206933 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f