SUNRPC: Fix compile on non-x86

current_task appears to be x86-only, oops.

Let's just delete this check entirely:

Any developer that adds a new user without setting rq_task will get a
crash the first time they test it.  I also don't think there are
normally any important locks held here, and I can't see any other reason
why killing a server thread would bring the whole box down.

So the effort to fail gracefully here looks like overkill.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 983c6844 "SUNRPC: get rid of the request wait queue"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/svc_xprt.c

@@ -771,10 +771,6 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
 			"svc_recv: service %p, transport not NULL!\n",
 			 rqstp);
 
-	/* Make sure the task pointer is set! */
-	if (WARN_ON_ONCE(!rqstp->rq_task))
-		rqstp->rq_task = current_task;
-
 	err = svc_alloc_arg(rqstp);
 	if (err)
 		return err;