target/riscv: Use aesdec_ISB_ISR_AK

This implements the AES64DS instruction.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/riscv/crypto_helper.c

@@ -213,7 +213,12 @@ target_ulong HELPER(aes64es)(target_ulong rs1, target_ulong rs2)
 
 target_ulong HELPER(aes64ds)(target_ulong rs1, target_ulong rs2)
 {
-    return aes64_operation(rs1, rs2, false, false);
+    AESState t;
+
+    t.d[HOST_BIG_ENDIAN] = rs1;
+    t.d[!HOST_BIG_ENDIAN] = rs2;
+    aesdec_ISB_ISR_AK(&t, &t, &aes_zero, false);
+    return t.d[HOST_BIG_ENDIAN];
 }
 
 target_ulong HELPER(aes64dsm)(target_ulong rs1, target_ulong rs2)