Fix incorrect check for LOG_UEVENTS

LOG_UEVENTS is a boolean value as defined in system/core/init/init.h.
Therefore, code should use an #if check and not an #ifdef check as the
macro will always be defined.

init/devices.c

@@ -288,7 +288,7 @@ static void make_device(const char *path, int block, int major, int minor)
     chown(path, uid, gid);
 }
 
-#ifdef LOG_UEVENTS
+#if LOG_UEVENTS
 
 static inline suseconds_t get_usecs(void)
 {