phy: mvebu-cp110-comphy: Update comment about powering off all lanes at boot

Now that all COMPHY modes are supported by the driver, update the
comment stating that mvebu_comphy_power_off() should be called for
each lane. This is still wrong because for compatibility reasons, it
might break users running an old firmware (the driver only uses SMC
calls for SATA, USB and PCIe configuration, there is no code in Linux
to fallback on in these cases.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>