IB/mlx4: Pass send queue sizes from userspace to kernel

Pass the number of WQEs for the send queue and their size from userspace
to the kernel to avoid having to keep the QP size calculations in sync 
between the kernel driver and libmlx4.  This fixes a bug seen with the 
current mlx4_ib driver and current libmlx4 caused by a difference in the 
calculated sizes for SQ WQEs.  Also, this gives more flexibility for 
userspace to experiment with using multiple WQE BBs for a single SQ WQE.

Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>