svc: Move kfree of deferral record to common code

The rqstp structure has a pointer to a svc_deferred_req record
that is allocated when requests are deferred. This record is common
to all transports and can be freed in common code.

Move the kfree of the rq_deferred to the common svc_xprt_release
function.

This also fixes a memory leak in the RDMA transport which does not
kfree the dr structure in it's version of the xpo_release_rqst callback.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 3fe4f10..2961961 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -448,6 +448,9 @@
 
 	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
 
+	kfree(rqstp->rq_deferred);
+	rqstp->rq_deferred = NULL;
+
 	svc_free_res_pages(rqstp);
 	rqstp->rq_res.page_len = 0;
 	rqstp->rq_res.page_base = 0;