MIPS: perf: Add hardware perf events support for new Loongson-3

New Loongson-3 means Loongson-3A R2 (Loongson-3A2000) and newer CPUs.
Loongson-3 processors have three types of PMU types (so there are three
event maps): Loongson-3A1000/Loonngson-3B1000/Loongson-3B1500 is Type-1,
Loongson-3A2000/Loongson-3A3000 is Type-2, Loongson-3A4000+ is Type-3.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>