target/riscv: fix ctzw behavior

According to spec, ctzw should work with 32-bit register, not 64.

For example, previous implementation returns 33 for (1<<33) input
when the new one returns 32.

Signed-off-by: Vladimir Isaev <vladimir.isaev@syntacore.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230204082312.43557-1-vladimir.isaev@syntacore.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/insn_trans/trans_rvb.c.inc

@@ -401,6 +401,7 @@ static bool trans_ctzw(DisasContext *ctx, arg_ctzw *a)
 {
     REQUIRE_64BIT(ctx);
     REQUIRE_ZBB(ctx);
+    ctx->ol = MXL_RV32;
     return gen_unary(ctx, a, EXT_ZERO, gen_ctzw);
 }