net: phy: export phy_suspend and phy_resume

phy_suspend and phy_resume are two commonly used helper functions that
need to be exported for Ethernet drivers to be built as modules

Fixes: 40755a0fce17 ("net: systemport: add suspend and resume support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>