Libsuspend: Remove unused variable

For build-system CFLAGS clean-up, remove unused variable.

Change-Id: I34bd33fd24b02ee58b64029146c253c61651d45f
diff --git a/libsuspend/autosuspend_autosleep.c b/libsuspend/autosuspend_autosleep.c
index 5451615..0d31e74 100644
--- a/libsuspend/autosuspend_autosleep.c
+++ b/libsuspend/autosuspend_autosleep.c
@@ -84,7 +84,6 @@
 
 struct autosuspend_ops *autosuspend_autosleep_init(void)
 {
-    int ret;
     char buf[80];
 
     autosleep_fd = open(SYS_POWER_AUTOSLEEP, O_WRONLY);