MIPS: Netlogic: Add support for XLP 3XX cores

Add new processor ID to asm/cpu.h and kernel/cpu-probe.c.
Update to new CPU frequency detection code which works on XLP 3XX
and 8XX.

Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2971/


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