target/loongarch: Implement vsllwil vextl

This patch includes:
- VSLLWIL.{H.B/W.H/D.W};
- VSLLWIL.{HU.BU/WU.HU/DU.WU};
- VEXTL.Q.D, VEXTL.QU.DU.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-24-gaosong@loongson.cn>
5 files changed