net: phy: qcom: move more function to shared library

Move more function to shared library in preparation for introduction of
new PHY Family qca807x that will make use of both functions from at803x
and qca808x as it's a transition PHY with some implementation of at803x
and some from the new qca808x.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>