mainboard/[g-l]: add IS_ENABLED() around Kconfig symbol references

Change-Id: I1f906c8c465108017bc4d08534653233078ef32d
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20343
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
52 files changed