USB: Prevent the funsoft serial device from entering raw mode

Added a device specific ioctl function to prevent the disabling of canonical
mode.  EINVAL is returned for any TCSETSF ioctl that doesn't have ICANON set.
This patch is for 2.6.17 or later kernels.

When "hwinfo --modem" is executed it opens the funsoft USB serial device and
disables canonical mode.  The device is kept this way until hwininfo has
finished probing any modems on a system.  The funsoft device expects to be
running in canonical mode.  Switching the device to raw mode can cause
incomplete data packets and device timeouts.

Signed-off-by: David Clare <david@funsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>