USB serial: add missing .usb_driver field in serial drivers

This patch (as1443) fixes a bug found in many of the USB serial
drivers: They don't set the .usb_driver field in their
usb_serial_driver structure.  This field is needed for assigning
dynamic IDs for device matching.

In addition, starting with the 2.6.37 kernel, the .usb_driver field is
needed for proper autosuspend operation.  Without it, attempts to open
the device file will fail.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Dan Williams <dcbw@redhat.com>
CC: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>