target-s390x: fix EXECUTE instruction executing TRT

A break is missing in the EXECUTE instruction, when executing the
TRANSLATE AND TEST instruction.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-By: Richard Henderson <rth@twiddle.net>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/target-s390x/mem_helper.c b/target-s390x/mem_helper.c
index 9f0eb1e..6f8bd79 100644
--- a/target-s390x/mem_helper.c
+++ b/target-s390x/mem_helper.c
@@ -482,6 +482,7 @@
         case 0xc00:
             helper_tr(env, l, get_address(env, 0, b1, d1),
                       get_address(env, 0, b2, d2));
+            break;
         case 0xd00:
             cc = helper_trt(env, l, get_address(env, 0, b1, d1),
                             get_address(env, 0, b2, d2));