net: phy: Fix sfp.c build against GPIO definitions

include/gpio.h does not contain the references we want, we should be including
linux/gpio/consumer.h instead.

Fixes: 73970055 ("sfp: add SFP module support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>