docs: fix code sample (#16623)

docs/feature_pointing_device.md

@@ -325,7 +325,8 @@ report_mouse_t pointing_device_task_user(report_mouse_t mouse_report) {
     if (set_scrolling) {
         mouse_report.h = mouse_report.x;
         mouse_report.v = mouse_report.y;
-        mouse_report.x = mouse_report.y = 0
+        mouse_report.x = 0;
+        mouse_report.y = 0;
     }
     return mouse_report;
 }