TFTF: Add ARMv8.5 BTI-related definitions

This patch adds BTI-related definitions in header files
which fully correspond to those in TF-A source tree.

Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Change-Id: I1ae4c13dab41b0099517dd1bead221909511f2fc
diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index 718964e..2d2a892 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -235,6 +235,11 @@
 
 #define SSBS_UNAVAILABLE	ULL(0)	/* No architectural SSBS support */
 
+#define ID_AA64PFR1_EL1_BT_SHIFT	U(0)
+#define ID_AA64PFR1_EL1_BT_MASK		ULL(0xf)
+
+#define BTI_IMPLEMENTED		ULL(1)	/* The BTI mechanism is implemented */
+
 #define ID_AA64PFR1_EL1_MTE_SHIFT	U(8)
 #define ID_AA64PFR1_EL1_MTE_MASK	ULL(0xf)