Remove extern keyword from function declarations

Function declarations implicitly have external linkage so do not
need the extern keyword.

Change-Id: Ia0549786796d8bf5956487e8996450a0b3d79f32
diff --git a/include/bl32/bl32.h b/include/bl32/bl32.h
index 3239487..ede7c48 100644
--- a/include/bl32/bl32.h
+++ b/include/bl32/bl32.h
@@ -41,8 +41,8 @@
 /******************************************
  * Function prototypes
  *****************************************/
-extern void bl32_platform_setup(void);
-extern struct meminfo *bl32_plat_sec_mem_layout(void);
-extern uint64_t bl32_main(void);
+void bl32_platform_setup(void);
+struct meminfo *bl32_plat_sec_mem_layout(void);
+uint64_t bl32_main(void);
 
 #endif /* __BL32_H__ */