clk: berlin: add support for berlin plls

This drivers allows to provide DT clocks for the cpu and system PLLs found on
Marvell Berlin SoCs.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
ARM: berlin/dt: add cpupll and syspll support to BG2Q

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
ARM: berlin/dt: add cpupll and syspll support to BG2CD

This also removes the clocks from the clocks container not and put them under
the root.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>