amiserial: remove incorrect 'no termios change' check

Lots of serial drivers check and optimise for setting the termios values to
the ones they were before.  This is pointless and the check is wrong
anyway.  Remove the checks on the serial drivers.  If we ever do need such
a check put it back in the tty layer instead _once_!

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