riscv: dts: thead: Add device tree VO clock controller

riscv: dts: thead: Add device tree VO clock controller

VO clocks reside in a different address space from the AP clocks on the
T-HEAD SoC. Add the device tree node of a clock-controller to handle
VO address space as well.

Reviewed-by: Drew Fustini <drew@pdp7.com>
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Signed-off-by: Drew Fustini <drew@pdp7.com>