net: dsa: b53: Uninitialized variable in b53_adjust_link()

The "pause" variable is only initialized on BCM5301x.

Fixes: 5e004460 ("net: dsa: b53: Add helper to set link parameters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>