target/loongarch: Implement vmskltz/vmskgez/vmsknz

This patch includes:
- VMSKLTZ.{B/H/W/D};
- VMSKGEZ.B;
- VMSKNZ.B.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-21-gaosong@loongson.cn>
5 files changed