arm: mvebu: NAND clock support for MSYS devices

arm: mvebu: NAND clock support for MSYS devices

One difference with the integrated CPUs is that they use a different
clock control block to the Armada devices. Update mvebu_get_nand_clock()
accordingly.

Signed-off-by: Chris Packham <[email protected]>
Reviewed-by: Stefan Roese <[email protected]>
Signed-off-by: Stefan Roese <[email protected]>