soc/intel/*: Make FSP header path user configurable

Required to compensate for Chrome OS' tree differences

Change-Id: I01fe80b55c69ff57da1c96a76bd1d9b5a2d4a9a8
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/29293
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
diff --git a/src/soc/intel/icelake/Kconfig b/src/soc/intel/icelake/Kconfig
index bc13f4f..664add2 100644
--- a/src/soc/intel/icelake/Kconfig
+++ b/src/soc/intel/icelake/Kconfig
@@ -200,7 +200,7 @@
 endchoice
 
 config FSP_HEADER_PATH
-	string
+	string "Location of FSP headers"
 	default "src/vendorcode/intel/fsp/fsp2_0/icelake/"
 
 config FSP_FD_PATH