target/riscv: fix clzw implementation to operate on arg1

The refactored gen_clzw() uses ret as its argument, instead of arg1.
Fix it.

Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210911140016.834071-3-philipp.tomsich@vrull.eu
Fixes: 6090391505 ("target/riscv: Add DisasExtend to gen_unary")
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/insn_trans/trans_rvb.c.inc

@@ -349,7 +349,7 @@ GEN_TRANS_SHADD(3)
 
 static void gen_clzw(TCGv ret, TCGv arg1)
 {
-    tcg_gen_clzi_tl(ret, ret, 64);
+    tcg_gen_clzi_tl(ret, arg1, 64);
     tcg_gen_subi_tl(ret, ret, 32);
 }