isicom: prepare for lock_kernel push down

Again lock the bits we can't trivially prove are safe without the BKL and
remove the broken TIOCS/GSOFTCAR handler.

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>