net: phy: phylink: Use gpiod_get_value_cansleep()

The GPIO provider for the link GPIO line might require the use of the
_cansleep() API, utilize that. This is safe to do since we run in workqueue
context.

Fixes: 9525ae83

 ("phylink: add phylink infrastructure")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>