toolbox: uptime: fix unused parameter warnings

Change-Id: Id240ce85bf09e1a81f4e2e2a7496ac7952edbf38
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/toolbox/uptime.c b/toolbox/uptime.c
index 1c312b0..455e7be 100644
--- a/toolbox/uptime.c
+++ b/toolbox/uptime.c
@@ -71,7 +71,8 @@
     return -1;
 }
 
-int uptime_main(int argc, char *argv[])
+int uptime_main(int argc __attribute__((unused)),
+        char *argv[] __attribute__((unused)))
 {
     float up_time, idle_time;
     char up_string[100], idle_string[100], sleep_string[100];