MIPS: Netlogic: XLP CPU support.

Add support for Netlogic's XLP MIPS SoC. This patch adds:
* XLP processor ID in cpu_probe.c and asm/cpu.h
* XLP case to asm/module.h
* CPU_XLP case to mm/tlbex.c
* minor change to r4k cache handling to ignore XLP secondary cache
* XLP cpu overrides to mach-netlogic/cpu-feature-overrides.h

Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2966/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>