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/common/arm_pm.c b/plat/arm/common/arm_pm.c
index 4ce13aa..cb87baf 100644
--- a/plat/arm/common/arm_pm.c
+++ b/plat/arm/common/arm_pm.c
@@ -11,10 +11,9 @@
 
 #include <arch_helpers.h>
 #include <lib/psci/psci.h>
+#include <plat/arm/common/plat_arm.h>
 #include <plat/common/platform.h>
 
-#include <plat_arm.h>
-
 /* Allow ARM Standard platforms to override these functions */
 #pragma weak plat_arm_program_trusted_mailbox