mainboard/[m-w]: add IS_ENABLED() around Kconfig symbol references

Change-Id: Ifba3257b0328d0b6ad1bee9bf885683998df5851
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20344
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
40 files changed