net: mdio: add ipq8064 mdio driver

Currently ipq806x soc use generic bitbang driver to
comunicate with the gmac ethernet interface.
Add a dedicated driver created by chunkeey to fix this.

Co-developed-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>