net: macb: fix wakeup test in runtime suspend/resume routines

Use the proper struct device pointer to check if the wakeup flag
and wakeup source are positioned.
Use the one passed by function call which is equivalent to
&bp->dev->dev.parent.

It's preventing the trigger of a spurious interrupt in case the
Wake-on-Lan feature is used.

Fixes: d54f89af ("net: macb: Add pm runtime support")
Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: Harini Katakam <harini.katakam@xilinx.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>