xprtrdma: Correct some documenting comments

Fix kernel-doc warnings in net/sunrpc/xprtrdma/ .

net/sunrpc/xprtrdma/verbs.c:1575: warning: No description found for parameter 'count'
net/sunrpc/xprtrdma/verbs.c:1575: warning: Excess function parameter 'min_reqs' description in 'rpcrdma_ep_post_extra_recv'

net/sunrpc/xprtrdma/backchannel.c:288: warning: No description found for parameter 'r_xprt'
net/sunrpc/xprtrdma/backchannel.c:288: warning: Excess function parameter 'xprt' description in 'rpcrdma_bc_receive_call'

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/backchannel.c

@@ -294,7 +294,7 @@ void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst)
 
 /**
  * rpcrdma_bc_receive_call - Handle a backward direction call
- * @xprt: transport receiving the call
+ * @r_xprt: transport receiving the call
  * @rep: receive buffer containing the call
  *
  * Operational assumptions:

net/sunrpc/xprtrdma/verbs.c

@@ -1584,7 +1584,7 @@ out_map:
 /**
  * rpcrdma_ep_post_extra_recv - Post buffers for incoming backchannel requests
  * @r_xprt: transport associated with these backchannel resources
- * @min_reqs: minimum number of incoming requests expected
+ * @count: minimum number of incoming requests expected
  *
  * Returns zero if all requested buffers were posted, or a negative errno.
  */