ARM: mvebu: add missing of_node_put() call in coherency.c

There is a missing of_node_put() to decrement the device_node
reference counter after a of_find_matching_node() in coherency_init().

Fixes: 501f928e

 ("ARM: mvebu: add a coherency_available() call")
Cc: <stable@vger.kernel.org> # v3.16+
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/1414423955-5933-4-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>