charger: fix build

Looks like libsuspend is not available on all platforms.

Change-Id: Ic32dc93221f3c488e846da35235f247f4ddb4c69
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/charger/charger.c b/charger/charger.c
index 1bacc81..25b3b1a 100644
--- a/charger/charger.c
+++ b/charger/charger.c
@@ -41,7 +41,9 @@
 #include <cutils/misc.h>
 #include <cutils/uevent.h>
 
+#ifdef CHARGER_ENABLE_SUSPEND
 #include <suspend/autosuspend.h>
+#endif
 
 #include "minui/minui.h"