tablet-tool: add usb_vendor_id and usb_product_id to wlr_tablet

backend/libinput/tablet_tool.c

@@ -22,6 +22,8 @@ void init_device_tablet(struct wlr_libinput_input_device *dev) {
 	wlr_tablet_init(wlr_tablet, &libinput_tablet_impl, name);
 	wlr_tablet->base.vendor = libinput_device_get_id_vendor(dev->handle);
 	wlr_tablet->base.product = libinput_device_get_id_product(dev->handle);
+	wlr_tablet->usb_vendor_id = libinput_device_get_id_vendor(dev->handle);
+	wlr_tablet->usb_product_id = libinput_device_get_id_product(dev->handle);
 
 	libinput_device_get_size(dev->handle, &wlr_tablet->width_mm,
 		&wlr_tablet->height_mm);

backend/wayland/tablet_v2.c

@@ -815,6 +815,8 @@ static void handle_tablet_id(void *data, struct zwp_tablet_v2 *zwp_tablet_v2,
 
 	tablet->base.vendor = vid;
 	tablet->base.product = pid;
+	tablet->usb_vendor_id = vid;
+	tablet->usb_product_id = pid;
 }
 
 static void handle_tablet_path(void *data, struct zwp_tablet_v2 *zwp_tablet_v2,

include/wlr/types/wlr_tablet_tool.h

@@ -64,6 +64,7 @@ struct wlr_tablet {
 
 	const struct wlr_tablet_impl *impl;
 
+	uint16_t usb_vendor_id, usb_product_id; // zero if unset
 	double width_mm, height_mm;
 
 	struct {