drm/drm_file.c: Define drm_send_event_helper() as 'static'

drm_send_event_helper() has not prototype, it has internal linkage and
therefore it should be defined with storage class 'static'.
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210427105503.10765-1-fmdefrancesco@gmail.com

drivers/gpu/drm/drm_file.c

@@ -774,19 +774,7 @@ void drm_event_cancel_free(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_event_cancel_free);
 
-/**
- * drm_send_event_helper - send DRM event to file descriptor
- * @dev: DRM device
- * @e: DRM event to deliver
- * @timestamp: timestamp to set for the fence event in kernel's CLOCK_MONOTONIC
- * time domain
- *
- * This helper function sends the event @e, initialized with
- * drm_event_reserve_init(), to its associated userspace DRM file.
- * The timestamp variant of dma_fence_signal is used when the caller
- * sends a valid timestamp.
- */
-void drm_send_event_helper(struct drm_device *dev,
+static void drm_send_event_helper(struct drm_device *dev,
 			   struct drm_pending_event *e, ktime_t timestamp)
 {
 	assert_spin_locked(&dev->event_lock);