target/riscv: Use REQUIRE_64BIT in amo_check64

Use the same REQUIRE_64BIT check that we use elsewhere,
rather than open-coding the use of is_32bit.

Reviewed-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20211020031709.359469-7-richard.henderson@linaro.org
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/insn_trans/trans_rvv.c.inc

@@ -743,7 +743,8 @@ static bool amo_check(DisasContext *s, arg_rwdvm* a)
 
 static bool amo_check64(DisasContext *s, arg_rwdvm* a)
 {
-    return !is_32bit(s) && amo_check(s, a);
+    REQUIRE_64BIT(s);
+    return amo_check(s, a);
 }
 
 GEN_VEXT_TRANS(vamoswapw_v, 0, rwdvm, amo_op, amo_check)