ARM: mvebu: don't use clocks property in UART node for Netgear RN2120

ARM: mvebu: don't use clocks property in UART node for Netgear RN2120

The Netgear RN2120 was not using the same strategy as the other Armada
370/375/38x/XP boards: it was using a 'clocks' property and not the
'clock-frequency' property in its UART controller Device Tree node.

However, now that this clock reference is present at the SoC-level,
there is no point in duplicating it at the board-level.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397806908-7550-6-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>