ip2: remove unneeded NULL check

We don't pass NULL tty pointers to the close function, and anyway we
already dereferenced it at this point.  This check can be removed.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: "Michael H. Warfield" <mhw@wittsend.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>