staging: android: sync: fix up a sparse warning

Fix up a sparse warning about sync_dump that was reported.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Erik Gilling <konkers@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/sync.c

@@ -988,7 +988,7 @@ late_initcall(sync_debugfs_init);
 
 #define DUMP_CHUNK 256
 static char sync_dump_buf[64 * 1024];
-void sync_dump(void)
+static void sync_dump(void)
 {
 	struct seq_file s = {
 		.buf = sync_dump_buf,