net: phy: move definition of genphy_c45_driver to phy_device.c

genphy_c45_read_status() is exported, so we can move definition of
genphy_c45_driver to phy_device.c and make it static. This helps
to clean up phy.h a little.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/ead3ab17-22d0-4cd3-901c-3d493ab851e6@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>