SVCRDMA: Fix erroneous BUG_ON in send_write

The assertion that checks for sge context overflow is
incorrectly hard-coded to 32. This causes a kernel bug
check when using big-data mounts. Changed the BUG_ON to
use the computed value RPCSVC_MAXPAGES.
Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/sunrpc/xprtrdma/svc_rdma_sendto.c

@@ -156,7 +156,7 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
 	struct svc_rdma_op_ctxt *ctxt;
 	int ret = 0;
 
-	BUG_ON(sge_count >= 32);
+	BUG_ON(sge_count > RPCSVC_MAXPAGES);
 	dprintk("svcrdma: RDMA_WRITE rmr=%x, to=%llx, xdr_off=%d, "
 		"write_len=%d, xdr_sge=%p, sge_count=%d\n",
 		rmr, (unsigned long long)to, xdr_off,