target/loongarch: Implement xvmskltz/xvmskgez/xvmsknz

This patch includes:
- XVMSKLTZ.{B/H/W/D};
- XVMSKGEZ.B;
- XVMSKNZ.B.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230914022645.1151356-33-gaosong@loongson.cn>
4 files changed