devlink: double free in devlink_resource_fill()

Smatch reports that devlink_dpipe_send_and_alloc_skb() frees the skb
on error so this is a double free.  We fixed a bunch of these bugs in
commit 7fe4d6dc ("devlink: Remove redundant free on error path") but
we accidentally overlooked this one.

Fixes: d9f9b9a4 ("devlink: Add support for resource abstraction")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>