IB/hfi1: Update RMT size calculation

IB/hfi1: Update RMT size calculation

Fix possible RMT overflow:  Use the correct netdev size.
Don't allow adjusted user contexts to go negative.

Fix QOS calculation: Send kernel context count as an argument since
dd->n_krcv_queues is not yet set up in earliest call.  Do not include
the control context in the QOS calculation.  Use the same sized
variable to find the max of krcvq[] entries.

Update the RMT count explanation to make more sense.

Signed-off-by: Dean Luick <dean.luick@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Link: https://lore.kernel.org/r/167329106946.1472990.18385495251650939054.stgit@awfm-02.cornelisnetworks.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>