refactor: convert arm platforms to use the generic GIC driver

This reduces the code the platforms have to carry and makes their build
rules a bit simpler.

The main benefit is that plat_my_core_pos() no longer needs to be called
within the driver, helping with performance a bit.

Change-Id: I0b0d1d36d20d67c41c8c9dc14ade11bda6d4a6af
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/plat/arm/common/arm_pm.c b/plat/arm/common/arm_pm.c
index 3e6c9f2..e8d15f7 100644
--- a/plat/arm/common/arm_pm.c
+++ b/plat/arm/common/arm_pm.c
@@ -148,7 +148,7 @@
 	/* Assert system power domain is available on the platform */
 	assert(PLAT_MAX_PWR_LVL >= ARM_PWR_LVL2);
 
-	plat_arm_gic_save();
+	gic_save();
 
 	/*
 	 * Unregister console now so that it is not registered for a second
@@ -177,7 +177,7 @@
 	/* Assert system power domain is available on the platform */
 	assert(PLAT_MAX_PWR_LVL >= ARM_PWR_LVL2);
 
-	plat_arm_gic_resume();
+	gic_resume();
 
 	plat_arm_security_setup();
 	arm_configure_sys_timer();