plat/arm: Sanitise includes

Use full include paths like it is done for common includes.

This cleanup was started in commit d40e0e08283a ("Sanitise includes
across codebase"), but it only cleaned common files and drivers. This
patch does the same to Arm platforms.

Change-Id: If982e6450bbe84dceb56d464e282bcf5d6d9ab9b
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/arm/css/common/css_bl2u_setup.c b/plat/arm/css/common/css_bl2u_setup.c
index 564e98f..c3b4f2b 100644
--- a/plat/arm/css/common/css_bl2u_setup.c
+++ b/plat/arm/css/common/css_bl2u_setup.c
@@ -6,10 +6,9 @@
 
 #include <common/bl_common.h>
 #include <common/debug.h>
+#include <plat/arm/common/plat_arm.h>
 #include <plat/common/platform.h>
 
-#include <plat_arm.h>
-
 #include "../drivers/scp/css_scp.h"
 
 /* Weak definition may be overridden in specific CSS based platform */