rose: Add length checks to CALL_REQUEST parsing

Define some constant offsets for CALL_REQUEST based on the description
at <http://www.techfest.com/networking/wan/x25plp.htm> and the
definition of ROSE as using 10-digit (5-byte) addresses.  Use them
consistently.  Validate all implicit and explicit facilities lengths.
Validate the address length byte rather than either trusting or
assuming its value.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
void rose_loopback_init(void)
{
	skb_queue_head_init(&loopback_queue);

	init_timer(&loopback_timer);
}

void rose_loopback_init(void)
{
	skb_queue_head_init(&loopback_queue);

	init_timer(&loopback_timer);
}
