IB/srp: Move ib_destroy_cm_id() call into srp_free_ch_ib()
IB/srp: Separate target and channel variables

Changes:
* Moved channel variables into a new structure (struct srp_rdma_ch).
* Added srp_target_port.ch_list and srp_rdma_ch.lock, entry, target
  and comp_vector.
* cm_id and completion handler context pointer is now of type
  srp_rdma_ch * instead of srp_target_port *.
IB/srp: Add multichannel support

Improve performance by using multiple RDMA/RC channels per SCSI host
for communicating with an SRP target.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
IB/srp: Reset requests before reallocating a QP
IB/srp: Add use_blk_mq kernel module parameter
IB/srp: Build fix for kernel 3.14
IB/srp: Remove stale connection retry mechanism
IB/srp: Move more member variables from target to channel
IB/srp: RDMA/CM support
IB/srp: OFED 3.12 build fix
Makefile: Rework OFED support