phy: marvell: add SATA comphy RX/TX polarity invert support

This patch adds support to Armada 7k/8k comphy RX/TX lane swap. The
'phy-invert' DT property defines the inverted signals.

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>