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/drivers/arm/cci400.h b/include/drivers/arm/cci400.h
index 3921675..7222391 100644
--- a/include/drivers/arm/cci400.h
+++ b/include/drivers/arm/cci400.h
@@ -66,7 +66,7 @@
 #define CHANGE_PENDING_BIT		(1 << 0)
 
 /* Function declarations */
-extern void cci_enable_coherency(unsigned long mpidr);
-extern void cci_disable_coherency(unsigned long mpidr);
+void cci_enable_coherency(unsigned long mpidr);
+void cci_disable_coherency(unsigned long mpidr);
 
 #endif /* __CCI_400_H__ */