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>

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"
 
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