ntb: intel: Fix using link status DB's

[ Upstream commit 8144e9c8f30fb23bb736a5d24d5c9d46965563c4 ]

Make sure we are not using DB's which were remapped for link status.

Fixes: f6e51c35 ("ntb: intel: split out the gen3 code")
Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Sasha Levin <sashal@kernel.org>