FILO: Pass LIBCONFIG_PATH variable to FILOs make

This fixes the build for HEAD/master.
Current stable will not work, because it is too old for recent corboot.

Change-Id: I9dfd5de472d4f58f07147cb9b9bb0b543f228561
Signed-off-by: Thomas Gstädtner <thomas@gstaedtner.net>
Reviewed-on: http://review.coreboot.org/311
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
diff --git a/payloads/external/FILO/Makefile.inc b/payloads/external/FILO/Makefile.inc
index 229b8be..311b3c8 100644
--- a/payloads/external/FILO/Makefile.inc
+++ b/payloads/external/FILO/Makefile.inc
@@ -20,7 +20,7 @@
 
 config: libpayload
 	echo "    CONFIG     FILO $(NAME-y)"
-	$(MAKE) -C filo defconfig
+	$(MAKE) -C filo defconfig LIBCONFIG_PATH=../../../libpayload
 	echo "CONFIG_COREBOOT=y" >> filo/.config
 	echo "CONFIG_DEBUG_SERIAL=y" >> filo/.config
 	echo "CONFIG_COREBOOT_FLASH=y" >> filo/.config