libevdev: Downgrade Event_Sync_State warning to debug.

Use LOG_DEBUG rather than LOG_WARNING for an informative
message that spams Chrome's log at startup:

  Event_Sync_State: before 39.191955 after 39.191960

BUG=none
TEST=none

Change-Id: I0ae31e0c5630ba2da012d24c070c659141ee5013
Reviewed-on: https://chromium-review.googlesource.com/386676
Commit-Ready: Dan Erat <derat@chromium.org>
Tested-by: Dan Erat <derat@chromium.org>
Reviewed-by: Charlie Mooney <charliemooney@chromium.org>
diff --git a/src/libevdev_event.c b/src/libevdev_event.c
index f284b26..4df9d4a 100755
--- a/src/libevdev_event.c
+++ b/src/libevdev_event.c
@@ -414,11 +414,11 @@
     /* Initialize EV_REL event state */
     Event_Clear_Ev_Rel_State(device);
 
-    LOG_WARNING(device, "Event_Sync_State: before %ld.%ld after %ld.%ld\n",
-                (long)device->before_sync_time.tv_sec,
-                (long)device->before_sync_time.tv_usec,
-                (long)device->after_sync_time.tv_sec,
-                (long)device->after_sync_time.tv_usec);
+    LOG_DEBUG(device, "Event_Sync_State: before %ld.%ld after %ld.%ld\n",
+              (long)device->before_sync_time.tv_sec,
+              (long)device->before_sync_time.tv_usec,
+              (long)device->after_sync_time.tv_sec,
+              (long)device->after_sync_time.tv_usec);
 }
 
 static void