USB: last abuses of intfdata in close for usb-serial drivers

these drivers abused intfdata in close() as flags for binding.
That races with reprobing of those devices. This patch fixes that by using
the flag and the locks introduced with the patch against mos7720.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>