usb: kill USB_MSG_RESET

The USB subsystem pipes internal reset notifications through
usb_handle_packet() with a special magic PID.  This indirection
is a pretty pointless excercise as it ends up being handled by
usb_generic_handle_packet anyway.

Replace the USB_MSG_RESET with a usb_device_reset() function
which can be called directly.  Also rename the existing usb_reset()
function to usb_port_reset() to avoid confusion.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>