NTB: Change WARN_ON_ONCE to pr_warn_once on unsafe

The unsafe doorbell and scratchpad access should display reason when
WARN is called.  Otherwise we get a stack dump without any explanation.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
1 file changed