ich_descriptors: Draw +0xfff into ICH_FREG_LIMIT()

The condition `base > limit` is still valid since `base` is always at
least 4096 greater than `limit` in this case.

Change-Id: I11ac0a50b3f32f47879e7cfb7a26068cd0572ede
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/19046
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
4 files changed