clk: mvebu: armada-37xx-periph: save the IP base address in the driver data

Prepare the introduction of suspend/resume hooks by having an easy way
to access all the registers in one go just from a device: add the IP
base address in the driver data.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>