target/loongarch: Implement xvssrln xvssran

This patch includes:
- XVSSRLN.{B.H/H.W/W.D};
- XVSSRAN.{B.H/H.W/W.D};
- XVSSRLN.{BU.H/HU.W/WU.D};
- XVSSRAN.{BU.H/HU.W/WU.D};
- XVSSRLNI.{B.H/H.W/W.D/D.Q};
- XVSSRANI.{B.H/H.W/W.D/D.Q};
- XVSSRLNI.{BU.H/HU.W/WU.D/DU.Q};
- XVSSRANI.{BU.H/HU.W/WU.D/DU.Q}.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230914022645.1151356-41-gaosong@loongson.cn>
4 files changed