MIPS: R3000/R3081: Fix CPU detection.

Broken since e05ea74fc56f347f872ef9946d27c53e8bf20864 (lmo) rsp.
cea7e2df (kernel.org) [MIPS: Sort out CPU
type to name translation.]  These CPUs are no longer very popular to say
the least ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Murphy McCauley <murphy.mccauley@gmail.com>