Throw an error if androidboot.hardware is used for bootconfig

Bootconfig does not allow the keys to have values and subkeys at the
same time.
"androidboot.hardware" and "androidboot.hardware.*" subkeys have existed as
kernel cmdline parameters. We want to throw an error at build time when
"androidboot.hardware" is use in bootconfig because it may be a common
occurence while migrating to bootconfig.
"hardware" should be used instead, without the "androidboot" prefix.

Test: build with and without "androidboot.hardware=test" in
BOARD_BOOTCONFIG
Bug: 173815685

Change-Id: Ic62a86cb23c9d79dbdbacd18eed3449210566ce7
diff --git a/core/Makefile b/core/Makefile
index a67d02a..38ce2fa 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1022,6 +1022,11 @@
 endif
 
 ifdef INTERNAL_BOOTCONFIG
+ifneq (,$(findstring androidboot.hardware=, $(INTERNAL_BOOTCONFIG)))
+$(error "androidboot.hardware" BOOTCONFIG parameter is not supported due to \
+  bootconfig limitations. Use "hardware" instead. INTERNAL_BOOTCONFIG: \
+  $(INTERNAL_BOOTCONFIG))
+endif
 INTERNAL_VENDOR_BOOTCONFIG_TARGET := $(PRODUCT_OUT)/vendor-bootconfig.img
 $(INTERNAL_VENDOR_BOOTCONFIG_TARGET):
 	rm -f $@