genericserial: remove bogus optimisation check and dead code paths

We've been using the 'new locking' for a long time now so it seems
pointless keeping the old one around.  Remove it and undo the macros it
uses back into real code for readability.  Remove the bogus 'no termios
change' checks.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Morten Helgesen <morten@sourcepoet.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>