ARM: dts: kirkwood: enable phy driver for SATA controller on 88f6192

This patch enables the phy drivers for the SATA controller on Marvell's 88f6192.
Without them it is not possible to use SATA drives attached to this processor.

Signed-off-by: Evgeni Dobrev <evgeni@studio-punkt.com>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>