clk: mmp: Add Marvell PXA1908 MPMU driver

Add driver for the MPMU controller block on Marvell's PXA1908 SoC. The
driver is incomplete, currently only supporting the fixed PLL1; dynamic
PLLs 2-4 and CPU/DDR/AXI clock support is missing.

Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Link: https://lore.kernel.org/r/20241104-pxa1908-lkml-v13-8-e050609b8d6c@skole.hr


Signed-off-by: Stephen Boyd <sboyd@kernel.org>