toolchain-external: Update Sourcery CodeBench MIPS toolchain

Update to the latest update for the 2013.05 toolchain
released on 11 September 2013.

https://sourcery.mentor.com/GNUToolchain/release2554



Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>