clk: mvebu: fix sscg node lookup

clk: mvebu: fix sscg node lookup

Commit 15917b16022427c53755abff4dc7051f3076dd7a ("clk: mvebu: Fix clk
frequency value if SSCG is enabled") introduced some logic in the
common mvebu clock code to adjust the clock frequency according to the
configuration of the SSCG.

In order to do this, it looks up for a DT node called "sscg" and maps
it before accessing the SSCG configuration register.

However, the lookup is currently done using:

	 sscg_np = of_find_node_by_name(np, "sscg");

where "np" is a pointer to the DT node of the clock for which we are
calculating the adjusted frequency. This means that if the "sscg" node
is *after* the clock node in the Device Tree, it works fine (and
that's the case for Armada 370).

However, if it turns out that the "sscg" node is *before* the clock
node in the Device Tree, it won't work because the sscg node will not
be found.

What we really want here is a search of the entire Device Tree, not
only starting from the clock node, so instead of passing "np" as first
argument of of_find_node_by_name(), we simply need to pass
NULL. Passing a non-NULL argument is typically used in a loop, so that
the search for the next matching node starts right after the node that
was matched.

This makes the "np" argument to the kirkwood_fix_sscg_deviation()
function unnecessary, which leads to further cleanups.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Fixes: 15917b1602242 ("clk: mvebu: Fix clk frequency value if SSCG is enabled")
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1410880503-2322-1-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>