net: phy: qcom: create and move functions to shared library

Create and move functions to shared library in preparation for qca83xx
PHY Family to be detached from at803x driver.

Only the shared defines are moved to the shared qcom.h header.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240129141600.2592-3-ansuelsmth@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>