USB: iuu_phoenix: remove unused MSR-wait queue

Remove unused, private modem-status wait queue from driver. If
TIOCMIWAIT is ever implemented it must not rely on a private wait queue
which may have been released when woken up.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>