phy: add A3700 COMPHY support

Add a driver to support COMPHY, a hardware block providing shared
serdes PHYs on Marvell Armada 3700. This driver uses SMC calls and
rely on having an up-to-date firmware.

SATA, PCie and USB3 host mode have been tested successfully with an
ESPRESSObin. (HS)SGMII mode cannot be tested with this platform.

Evan worked on the original driver structure and Grzegorz on the SMC
calls rework. The structure of this driver has been copied from
Antoine Tenart work on CP110 COMPHY driver.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Co-developed-by: Evan Wang <xswang@marvell.com>
Signed-off-by: Evan Wang <xswang@marvell.com>
Co-developed-by: Grzegorz Jaszczyk <jaz@semihalf.com>
Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>