net: phy: Fix modular PHYLIB build

net: phy: Fix modular PHYLIB build

After commit 3c77ce5a6491 ("net: Move PHY statistics code into PHY
library helpers") we made net/core/ethtool.c reference symbols which are
part of the library which can be modular. David introduced a temporary
fix with e043391213ed ("phy: Temporary build fix after phylib changes.")
which would prevent such modularity.

This is not desireable of course, so instead, just inline the functions
into include/linux/phy.h to keep both options available.

Fixes: 3c77ce5a6491 ("net: Move PHY statistics code into PHY library helpers")
Fixes: e043391213ed ("phy: Temporary build fix after phylib changes.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>