IB/hfi1: Indicate DMA wait when txq is queued for wakeup

There is no counter for dmawait in AIP, which hampers debugging
performance issues.

Add the counter increment when the txq is queued.

Fixes: d99dc602 ("IB/hfi1: Add functions to transmit datagram ipoib packets")
Link: https://lore.kernel.org/r/20210715160440.142451.8278.stgit@awfm-01.cornelisnetworks.com


Signed-off-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>