RDMA/nes: Change memory allocation for cqp request to GFP_ATOMIC

The routine to allocate a cqp request is not called from process
context code.  Since it is not OK to sleep, it needs to use GFP_ATOMIC
not GFP_KERNEL.

Signed-off-by: Don Wood <donald.e.wood@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>