ntb_transport: fix qp count bug

In cases where there are more mw's than spads/2-2, the mw count gets
reduced to match the limitation. ntb_transport also tries to ensure that
there are fewer qps than mws but uses the full mw count instead of
the reduced one. When this happens, the math in
'ntb_transport_setup_qp_mw' will get confused and result in a kernel
paging request bug.

This patch fixes the bug by reducing qp_count to the reduced mw count
instead of the full mw count.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Fixes: e26a5843 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>