fix(rpi3): use correct name for include guards

fixed rpi_shared.h include guard, previously the commented
endif was RPI3_PRIVATE, which could be a cause for confusion
when searching through header files.

Change-Id: I721f9f7c38cd14cda0385593b307cdfc71f810f8
Signed-off-by: Abhi Singh <abhi.singh@arm.com>
diff --git a/plat/rpi/common/include/rpi_shared.h b/plat/rpi/common/include/rpi_shared.h
index 8562c3d..d22fc64 100644
--- a/plat/rpi/common/include/rpi_shared.h
+++ b/plat/rpi/common/include/rpi_shared.h
@@ -52,4 +52,4 @@
 
 void plat_rpi_bl31_custom_setup(void);
 
-#endif /* RPI3_PRIVATE_H */
+#endif /* RPI3_SHARED_H */