net: pxa168_eth: fix Ethernet flow control status

IEEE 802.3x Ethernet flow control is disabled when bit (1 << 2) is set
in the port status register. Fix the flow control detection in the link
event handling function which was relying on the opposite assumption.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>