target/loongarch: Implement LASX fpu arith instructions

This patch includes:
- XVF{ADD/SUB/MUL/DIV}.{S/D};
- XVF{MADD/MSUB/NMADD/NMSUB}.{S/D};
- XVF{MAX/MIN}.{S/D};
- XVF{MAXA/MINA}.{S/D};
- XVFLOGB.{S/D};
- XVFCLASS.{S/D};
- XVF{SQRT/RECIP/RSQRT}.{S/D}.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230914022645.1151356-47-gaosong@loongson.cn>