Merge r239037,239050 from head:

Merge r239037,239050 from head:
  Support multiple interface devices.  The driver had previously hardcoded
  support for only the first port, but the CP2105 can have multiple ports.
  Although without this change the the first port mostly worked on multi
  port devices, there could still be issues with this arrangement.

  Update the man page to reflect support for both ports and the CP2105.

  Many thanks to Silicon Labs (www.silabs.com) for providing a CP2105-EK
  dev board for testing.

git-svn-id: svn://svn.freebsd.org/base/stable/8@239827 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f