RxRPC: Use kmemdup rather than duplicating its implementation

The semantic patch that makes this change is available
in scripts/coccinelle/api/memdup.cocci.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/ar-key.c b/net/rxrpc/ar-key.c
index 43ea7de..4cba13e 100644
--- a/net/rxrpc/ar-key.c
+++ b/net/rxrpc/ar-key.c
@@ -306,10 +306,9 @@
 	td->data_len = len;
 
 	if (len > 0) {
-		td->data = kmalloc(len, GFP_KERNEL);
+		td->data = kmemdup(xdr, len, GFP_KERNEL);
 		if (!td->data)
 			return -ENOMEM;
-		memcpy(td->data, xdr, len);
 		len = (len + 3) & ~3;
 		toklen -= len;
 		xdr += len >> 2;
@@ -401,10 +400,9 @@
 	_debug("ticket len %u", len);
 
 	if (len > 0) {
-		*_ticket = kmalloc(len, GFP_KERNEL);
+		*_ticket = kmemdup(xdr, len, GFP_KERNEL);
 		if (!*_ticket)
 			return -ENOMEM;
-		memcpy(*_ticket, xdr, len);
 		len = (len + 3) & ~3;
 		toklen -= len;
 		xdr += len >> 2;