s390x/tcg: specification exception for unknown diag

While the PoP is silent on the issue, z/VM documentation states
that unknown diagnose codes trigger a specification exception.
We already do that when running with kvm, so change tcg to do so
as well.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

target/s390x/misc_helper.c

@@ -109,7 +109,7 @@ void HELPER(diag)(CPUS390XState *env, uint32_t r1, uint32_t r3, uint32_t num)
     }
 
     if (r) {
-        program_interrupt(env, PGM_OPERATION, ILEN_AUTO);
+        program_interrupt(env, PGM_SPECIFICATION, ILEN_AUTO);
     }
 }