MIPS: detect presence of MAARs

Detect the presence of MAAR using the MRP bit in Config5, and record
that presence using a CPU option bit. A cpu_has_maar macro will then
allow code to conditionalise upon the presence of MAARs.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7330/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/include/asm/cpu-features.h
Simple merge

diff --cc arch/mips/include/asm/cpu.h
Simple merge

diff --cc arch/mips/kernel/cpu-probe.c
Simple merge