mb/Kconfig: Add a warning on boards with a ROMCC_BOOTLOCK

This feature and therefore the boards using it, will be deprecated
soon.

Change-Id: I1e970dd0613702346b5764d2b56012a72ed62cde
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37155
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/Kconfig b/src/mainboard/Kconfig
index c88d317..97086b7 100644
--- a/src/mainboard/Kconfig
+++ b/src/mainboard/Kconfig
@@ -1,5 +1,9 @@
 comment "Important: Run 'make distclean' before switching boards"
 
+if ROMCC_BOOTBLOCK
+comment "Systems with ROMCC bootblocks will be deprecated soon!"
+endif
+
 choice
 	prompt "Mainboard vendor"
 	default VENDOR_EMULATION