A set of tty line discipline cleanup patches were introduced before the
dawn of time, in kernel version 2.4.21.  This patch performs that cleanup
for the hvsi driver.

The hvsi driver is used only on IBM pSeries PowerPC boxes.  The driver was
originally written by Hollis Blanchard, who has delegated maintainership to
me.  So this my first and maybe only patch in this official new role,
because this driver is otherwise bug-free :-)

Alan: "Actually its also a bug fix, tty->ldisc should be locked by refcounting
and the helpers do this for you."
Signed-off-by: NLinas Vepstas <linas@austin.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>