Removes usage of TARGET_NO_VENDOR_BOOT.

- true -> PRODUCT_BUILD_VENDOR_BOOT_IMAGE=false
- false -> (removed, uses default option which builds vendor-boot.img
            if BOARD_BOOT_HEADER_VERSION>=3)

Bug: 170423509
Test: Inspect build artifacts from treehugger.
Change-Id: Id16fbda7fdfc70d62db389d6efb5201cb0d6d4e3
diff --git a/core/board_config.mk b/core/board_config.mk
index 05b6b29..7603a6d 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -378,12 +378,7 @@
 BUILDING_VENDOR_BOOT_IMAGE :=
 ifdef BOARD_BOOT_HEADER_VERSION
   ifneq ($(call math_gt_or_eq,$(BOARD_BOOT_HEADER_VERSION),3),)
-    ifneq ($(TARGET_NO_VENDOR_BOOT),)
-      $(warning TARGET_NO_VENDOR_BOOT has been deprecated. Please use PRODUCT_BUILD_VENDOR_BOOT_IMAGE.)
-      ifneq ($(TARGET_NO_VENDOR_BOOT),true)
-        BUILDING_VENDOR_BOOT_IMAGE := true
-      endif
-    else ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),)
+    ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),)
       BUILDING_VENDOR_BOOT_IMAGE := true
     else ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),true)
       BUILDING_VENDOR_BOOT_IMAGE := true