board_id: Remove extra quotes.

Kconfig already quotes the string. Double quoting actually removes the
quoting.

Change-Id: I927d90dc2ce8af4e8d2d700d2bb3e04254459e1b
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/10382
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/Makefile.inc b/Makefile.inc
index d5ef301..3e28709 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -639,7 +639,7 @@
 board_id-type := raw
 
 $(obj)/board_id:
-	printf "$(CONFIG_BOARD_ID_STRING)" > $@
+	printf $(CONFIG_BOARD_ID_STRING) > $@
 
 JENKINS_PAYLOAD=none
 what-jenkins-does: