fconf: Add TBBR disable_authentication property

Use fconf to retrieve the `disable_authentication` property.
Move this access from arm dynamic configuration to bl common.

Change-Id: Ibf184a5c6245d04839222f5457cf5e651f252b86
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index abf2f91..ceff6e2 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -273,7 +273,8 @@
     # Include common TBB sources
     AUTH_SOURCES	:=	drivers/auth/auth_mod.c				\
 				drivers/auth/crypto_mod.c			\
-				drivers/auth/img_parser_mod.c
+				drivers/auth/img_parser_mod.c			\
+				lib/fconf/fconf_tbbr_getter.c
 
     # Include the selected chain of trust sources.
     ifeq (${COT},tbbr)