MIPS: cache: optimise changing of k0 CCA mode

Changing the Cache Coherency Algorithm (CCA) for kernel mode
requires executing from KSEG1. Thus do a jump from KSEG0 to KSEG1
before changing the CCA mode. Jump back to KSEG0 afterwards.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>