Fix MISRA rule 8.5 in common code

Rule 8.5: An external object or function shall be declared
          once in one and only one file.

Change-Id: I7c3d4ec7d3ba763fdb4600008ba10b4b93ecdfce
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

include/bl2/bl2.h

@@ -7,9 +7,6 @@
 #ifndef BL2_H__
 #define BL2_H__
 
-struct entry_point_info;
-
 void bl2_main(void);
-struct entry_point_info *bl2_load_images(void);
 
 #endif /* BL2_H__ */