fix(build): include platform mk earlier

Move platform.mk inclusion in top level Makefile to permit a platform
specifying BRANCH_PROTECTION option.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I1f662f82cd949eedfdbb61b9f66de15c46fb3106
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 73d96c5..580ef5f 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -363,7 +363,7 @@
 endif
 
 # Pointer Authentication sources
-ifeq (${ENABLE_PAUTH}, 1)
+ifeq ($(BRANCH_PROTECTION),$(filter $(BRANCH_PROTECTION),1 2 3))
 PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c
 endif
 
diff --git a/plat/nuvoton/npcm845x/platform.mk b/plat/nuvoton/npcm845x/platform.mk
index 1959aac..d73756c 100644
--- a/plat/nuvoton/npcm845x/platform.mk
+++ b/plat/nuvoton/npcm845x/platform.mk
@@ -318,9 +318,8 @@
 endif
 
 # Pointer Authentication sources
-ifeq (${ENABLE_PAUTH}, 1)
-PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c \
-		lib/extensions/pauth/pauth_helpers.S
+ifeq ($(BRANCH_PROTECTION),$(filter $(BRANCH_PROTECTION),1 2 3))
+PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c
 endif
 
 ifeq (${SPD},spmd)
diff --git a/plat/qemu/common/common.mk b/plat/qemu/common/common.mk
index 51497bd..5e3a61a 100644
--- a/plat/qemu/common/common.mk
+++ b/plat/qemu/common/common.mk
@@ -149,9 +149,8 @@
 endif
 
 # Pointer Authentication sources
-ifeq (${ENABLE_PAUTH}, 1)
+ifeq ($(BRANCH_PROTECTION),$(filter $(BRANCH_PROTECTION),1 2 3))
 PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c
-CTX_INCLUDE_PAUTH_REGS	:=	1
 endif
 
 endif