bl1: include bl1_private.h in aarch* files

This change avoids warnings when setting -Wmissing-prototypes or when
using sparse tool.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
diff --git a/bl1/aarch64/bl1_context_mgmt.c b/bl1/aarch64/bl1_context_mgmt.c
index 2c7fe07..b9304dc 100644
--- a/bl1/aarch64/bl1_context_mgmt.c
+++ b/bl1/aarch64/bl1_context_mgmt.c
@@ -10,6 +10,7 @@
 #include <context_mgmt.h>
 #include <debug.h>
 #include <platform.h>
+#include "../bl1_private.h"
 
 /*
  * Following array will be used for context management.