Newer Marvell MVEBU SoC like Armada 370/XP have an additional core
clock divider for e.g. NAND clock. Add the corresponding driver based
on the Linux driver.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

This adds of_clk_providers for core clocks and clock gates found on
Marvell MVEBU SoCs (Armada 370, Armada XP, Dove, and Kirkwood).
It is based on Linux clock providers with clock flags removed, as they
are not used on Barebox.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>