net: calxedaxgmac: Wake-on-LAN fixes

WOL is broken because the magic packet status bit is getting set rather
than the enable bit. The PMT interrupt is not getting serviced because
the PMT interrupt is also enabled on the global interrupt, but not
cleared by the global interrupt and the global interrupt is higher
priority. This fixes both of these issues to get WOL working.

There's still a problem with receive after resume, but at least now we
can wake-up.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>