Revert "param: increase CQ read count to 16 for performance"

This reverts commit 346be40.

Revert commit since plans are to follow master branch on neuron
platforms. Since benefit of increase has not been verified yet, revert
change for now.

include/nccl_ofi_param.h

@@ -142,7 +142,7 @@ OFI_NCCL_PARAM_INT(mr_cache_disable, "MR_CACHE_DISABLE", 0);
  * Maximum number of cq entries to read in a single call to
  * fi_cq_read.
  */
-OFI_NCCL_PARAM_INT(cq_read_count, "CQ_READ_COUNT", 16);
+OFI_NCCL_PARAM_INT(cq_read_count, "CQ_READ_COUNT", 4);
 
 /*
  * Protocol to use for send/recv operations.  Valid options are