build: Allow target override from TARGET_PRODUCT

If defined, use $TARGET_BOOTLOADER_PLATFORM_OVERRIDE as
LK build target instead of $TARGET_PRODUCT.

Change-Id: I1444c261a7b8fd8202ace74c10c8dce097ea4263
diff --git a/AndroidBoot.mk b/AndroidBoot.mk
index a9ca944..bcf1c6f 100644
--- a/AndroidBoot.mk
+++ b/AndroidBoot.mk
@@ -7,6 +7,12 @@
   SIGNED_KERNEL := SIGNED_KERNEL=0
 endif
 
+ifneq ($(strip $(TARGET_BOOTLOADER_PLATFORM_OVERRIDE)),)
+  BOOTLOADER_PLATFORM := $(TARGET_BOOTLOADER_PLATFORM_OVERRIDE)
+else
+  BOOTLOADER_PLATFORM := $(TARGET_PRODUCT)
+endif
+
 # NAND variant output
 TARGET_NAND_BOOTLOADER := $(PRODUCT_OUT)/appsboot.mbn
 NAND_BOOTLOADER_OUT := $(TARGET_OUT_INTERMEDIATES)/NAND_BOOTLOADER_OBJ
@@ -30,11 +36,11 @@
 
 # Top level for NAND variant targets
 $(TARGET_NAND_BOOTLOADER): appsbootldr_clean | $(NAND_BOOTLOADER_OUT)
-	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(NAND_BOOTLOADER_OUT) $(TARGET_PRODUCT) $(SIGNED_KERNEL)
+	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(NAND_BOOTLOADER_OUT) $(BOOTLOADER_PLATFORM) $(SIGNED_KERNEL)
 
 # Top level for eMMC variant targets
 $(TARGET_EMMC_BOOTLOADER): emmc_appsbootldr_clean | $(EMMC_BOOTLOADER_OUT)
-	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(EMMC_BOOTLOADER_OUT) $(TARGET_PRODUCT) EMMC_BOOT=1 $(SIGNED_KERNEL)
+	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(EMMC_BOOTLOADER_OUT) $(BOOTLOADER_PLATFORM) EMMC_BOOT=1 $(SIGNED_KERNEL)
 
 # Keep build NAND & eMMC as default for targets still using TARGET_BOOTLOADER
 TARGET_BOOTLOADER := $(PRODUCT_OUT)/EMMCBOOT.MBN
@@ -43,7 +49,7 @@
 #
 # Build nandwrite as a part of Android Build for NAND configurations
 #
-TARGET_NANDWRITE := $(PRODUCT_OUT)/obj/nandwrite/build-$(TARGET_PRODUCT)_nandwrite/lk
+TARGET_NANDWRITE := $(PRODUCT_OUT)/obj/nandwrite/build-$(BOOTLOADER_PLATFORM)_nandwrite/lk
 NANDWRITE_OUT := $(TARGET_OUT_INTERMEDIATES)/nandwrite
 
 nandwrite_clean:
@@ -54,5 +60,5 @@
 	mkdir -p $(NANDWRITE_OUT)
 
 $(TARGET_NANDWRITE): nandwrite_clean | $(NANDWRITE_OUT)
-	@echo $(TARGET_PRODUCT)_nandwrite
-	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(NANDWRITE_OUT) $(TARGET_PRODUCT)_nandwrite BUILD_NANDWRITE=1
+	@echo $(BOOTLOADER_PLATFORM)_nandwrite
+	$(MAKE) -C bootable/bootloader/lk BOOTLOADER_OUT=../../../$(NANDWRITE_OUT) $(BOOTLOADER_PLATFORM)_nandwrite BUILD_NANDWRITE=1