dev-serial: replace DeviceOutVendor/DeviceInVendor with equivalent macros from usb.h

dev-serial: replace DeviceOutVendor/DeviceInVendor with equivalent macros from usb.h

The DeviceOutVendor and DeviceInVendor macros can be replaced with their
equivalent VendorDeviceOutRequest and VendorDeviceRequest macros from usb.h.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20201027150456.24606-6-mark.cave-ayland@ilande.co.uk
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>