target/loongarch: Implement xvsllwil xvextl

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

Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230914022645.1151356-37-gaosong@loongson.cn>