MN10300: SMP TLB flushing

Implement global TLB flushing for MN10300.  This will be used by the AM34 which
is SMP capable.

Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>