arm: dts: rk3399: Sync roc-pc-mezzanine from v5.7-rc1

Sync Firefly ROC-RK3399-PC Mezzanine Board dts file
from Linux v5.7-rc1.

Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>