usb serial: Add generic USB wwan support

The generic USB serial code is ill-suited for high-speed USB wwan devices,
resulting in the option driver. However, other non-option devices may also
gain similar benefits from not using the generic code. Factorise out the
non-option specific code from the option driver and make it available to
other users.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 3203614..e54c728 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -52,6 +52,7 @@
 obj-$(CONFIG_USB_SERIAL_SIERRAWIRELESS)		+= sierra.o
 obj-$(CONFIG_USB_SERIAL_SPCP8X5)		+= spcp8x5.o
 obj-$(CONFIG_USB_SERIAL_SYMBOL)			+= symbolserial.o
+obj-$(CONFIG_USB_SERIAL_WWAN)			+= usb_wwan.o
 obj-$(CONFIG_USB_SERIAL_TI)			+= ti_usb_3410_5052.o
 obj-$(CONFIG_USB_SERIAL_VISOR)			+= visor.o
 obj-$(CONFIG_USB_SERIAL_WHITEHEAT)		+= whiteheat.o