Fix MIPS SC

Fix botched merge of op_ldst_sc calls to match actual implementation.
Thanks to Aurelien Jarno for diagnosing this.

Signed-off-by: Paul Brook <paul@codesourcery.com>
diff --git a/target-mips/translate.c b/target-mips/translate.c
index cf467f8..cc8b329 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -1174,13 +1174,13 @@
 #if defined(TARGET_MIPS64)
     case OPC_SCD:
         save_cpu_state(ctx, 0);
-        op_ldst_scd(t0, t1, t0, ctx);
+        op_ldst_scd(t1, t0, rt, ctx);
         opn = "scd";
         break;
 #endif
     case OPC_SC:
         save_cpu_state(ctx, 0);
-        op_ldst_sc(t0, t1, t0, ctx);
+        op_ldst_sc(t1, t0, rt, ctx);
         opn = "sc";
         break;
     }