bna: Tx and Rx Optimizations

Change details:
 -      Have contiguous queue pages for TxQ, RxQ and CQ. Data structure and
        QPT changes related to contiguous queue pages
 -      Optimized Tx and Rx unmap structures. Tx and Rx fast path changes due to
        unmap data structure changes
 -      Re-factored Tx and Rx fastpath routines as per the new queue data structures
 -      Implemented bnad_txq_wi_prepare() to program the opcode, flags, frame_len
        and num_vectors in the work item
 -      Reduced Max TxQ and RxQ depth to 2048 while default value for Tx/Rx queue
        depth is unaltered (512)

Signed-off-by: Rasesh Mody <rmody@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>