scripts: update config.sub

Latest from upstream config-patches repo. (No change to config.guess)

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Message-Id: <f15b7c69c142e935391e.1350284600@localhost.localdomain>
Patchwork-Id: 191476

 reporter_name="Kevin Cernekee"

 reporter_url="http://sourceware.org/ml/crossgcc/2011-09/msg00037.html"

 reporter_comment="MIPS SDE-compatible toolchain"