net: phy: remove remaining PHY package related definitions from phy.h

Move definition of struct phy_package_shared to phy_package.c, and
move remaining PHY package related declarations from phy.h to
phylib.h, thus making them accessible for PHY drivers only.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/211e14b6-e2f8-43d7-b533-3628ec548456@gmail.com


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