km/ls102xa: dbg phy prst depends on piggy presence

km/ls102xa: dbg phy prst depends on piggy presence

The PHY for the debug interface was placed on the board for the
pg_wcom_ls102x. Hence only when a piggy is plugged, a RJ45 jack
including magnetics is connected to the MDI of the PHY. Without a
piggy the MDI lines are left floating and it does not make sense to
have an active debug PHY.
In case of expu1 an active PHY without a piggy even led to increased
jitter for syncE.

This patch only deactivates the prst line of the debug PHY when a piggy
is detected persent.

Signed-off-by: Rainer Boschung <rainer.boschung@hitachienergy.com>
Signed-off-by: Aleksandar Gerasimovski <aleksandar.gerasimovski@hitachienergy.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>