Create an UBIQUITI kernel configuration for mips. This
includes the OCTEON1 kernel configuration file, and sets
the OCTEON_VENDOR_UBIQUITI kernel option needed for the
UBIQUITI-based boards.

This kernel configuration is excluded from universe builds.

Note: This change may or may not be merged back to head,
pending feedback from juli@ on this change.

Sponsored by: The FreeBSD Foundation