Switch to generic tiocmiwait rather than rely on a custom implementation
using racy interruptible_sleep_on().

Note that this driver is mostly stubbed out so neither version of
tiocmiwait will actually work until someone implements
f81232_update_line_status().
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>