opal: remove unnecessary #include file

opal_config_bottom.h can only be #include'd in opal_config.h,
so there is no need to #include "opal_config.h" inside.

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>
(cherry picked from commit c8790d29de5ef399fd805f27366af6c2dc87ce9e)

opal/include/opal_config_bottom.h

@@ -260,7 +260,6 @@
    including stdint.h */
 #define __STDC_LIMIT_MACROS
 #endif
-#include "opal_config.h"
 #include "opal_stdint.h"
 
 /***********************************************************************