The calls to pm_runtime_force_suspend/resume() functions are only
relevant if the device is not configured to act as a WoL wakeup source.
Add the device_may_wakeup() test before calling them.

Fixes: 3e2a5e15 ("net: macb: add wake-on-lan support via magic packet")
Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: Harini Katakam <harini.katakam@xilinx.com>
Cc: Sergio Prado <sergio.prado@e-labworks.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>