USB: serial: fix stringify operator in usb-serial-simple

USB: serial: fix stringify operator in usb-serial-simple

usb-serial-simple uses an unknown stringify macro that make
all drivers being named "stringify(vendor)".

This can be a problem when two drivers have the same (wrong) name:

    kernel: usbcore: registered new interface driver usb_serial_simple
    kernel: usbserial: USB Serial support registered for stringify(vendor)
    kernel Error: Driver 'stringify(vendor)' is already registered, aborting...
    kernel: usbserial: problem -16 when registering driver stringify(vendor)
    kernel: usbserial: USB Serial deregistering driver stringify(vendor)
    kernel: usbcore: deregistering interface driver usb_serial_simple

Before the fix:

    $ strings drivers/usb/serial/usb-serial-simple.o
    usb_serial_simple
    stringify(vendor)

After the fix:

    $ strings drivers/usb/serial/usb-serial-simple.o
    usb_serial_simple
    funsoft
    flashloader
    vivopay
    moto_modem
    hp4x
    suunto
    siemens_mpi

This patch makes usb-serial-simple use the correct stringify operator.

Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>