chromebooks: Define GBB hardware IDs

This makes the test IDs the default, taken from depthcharge
master (board/*/fmap.dts, hwid property).

Change-Id: I25793962ac16f451f204dbba6ede6a64c847cfd5
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: https://review.coreboot.org/13634
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins)

src/mainboard/google/nyan/Kconfig

@@ -91,4 +91,8 @@ config DRIVER_TPM_I2C_ADDR
 	hex
 	default 0x20
 
+config GBB_HWID
+	string
+	depends on CHROMEOS
+	default "NYAN TEST 9382"
 endif # BOARD_GOOGLE_NYAN