68360serial: remove broken optimisation

Remove the broken 'no termios change' optimisation for this driver.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>