Add rule to support verified boot.

Enable verified boot code in LK.

Change-Id: I07362da0018a7f55137c06d9e6e603a0911dc26a
diff --git a/makefile b/makefile
index 1056726..252903e 100644
--- a/makefile
+++ b/makefile
@@ -97,6 +97,14 @@
 # Useful for header files that may be included by one or more source files.
 SRCDEPS := $(CONFIGHEADER)
 
+ifeq ($(VERIFIED_BOOT),1)
+  DEFINES += VERIFIED_BOOT=1
+  DEFINES += _SIGNED_KERNEL=1
+  ifeq ($(DEFAULT_UNLOCK),true)
+    DEFINES += DEFAULT_UNLOCK=1
+  endif
+endif
+
 # these need to be filled out by the project/target/platform rules.mk files
 TARGET :=
 PLATFORM :=