MIPS: SEAD3: Disable L2 cache on SEAD-3.

The cores used on the SEAD-3 platform do not have L2 caches, so
this option should not be turned on. Originally fixed on public
'linux-mti-3.8' release branch.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5559/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>