xen/netback: don't leak pages on failure in xen_netbk_tx_check_gop.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static void xen_netbk_alarm(unsigned long data)
{
	struct xen_netbk *netbk = (struct xen_netbk *)data;
	xen_netbk_kick_thread(netbk);
}

static void xen_netbk_alarm(unsigned long data)
{
	struct xen_netbk *netbk = (struct xen_netbk *)data;
	xen_netbk_kick_thread(netbk);
}
