target/riscv: fix return value of do_opivx_widen()

do_opivx_widen() should return false if check function returns false.

Backports a69f97c1110205bc173657c77ce2d16877cad683

qemu/target/riscv/insn_trans/trans_rvv.inc.c

@@ -1169,7 +1169,7 @@ static bool do_opivx_widen(DisasContext *s, arg_rmrr *a,
     if (opivx_widen_check(s, a)) {
         return opivx_trans(a->rd, a->rs1, a->rs2, a->vm, fn, s);
     }
-    return true;
+    return false;
 }
 
 #define GEN_OPIVX_WIDEN_TRANS(NAME) \