dt-bindings: mips: Add Loongson-2K1000 reset support

Switch the DT binding to a YAML schema to enable the DT validation.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>