Partially revert "clk: mvebu: Convert to clk_hw based provider APIs"

This partially reverts commit eca61c9f.

Thomas reports that it causes regressions on Armada XP devices.
This is because of_clk_get_parent_name() relies on the property
'clock-output-names' to resolve the name of a clock's parent,
without trying to get the clock from the framework and call
__clk_get_name(). Given that Armada XP devices don't have the
'clock-output-names' property, of_clk_get_parent_name() returns
the name of the node which doesn't match the actual parent
clock's name at all, causing CPU clocks to never link up with
their parents.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>