dt-bindings: clock: eswin: Documentation for eic7700 SoC

dt-bindings: clock: eswin: Documentation for eic7700 SoC

Add device tree binding documentation for the ESWIN eic7700
clock controller module.

Signed-off-by: Yifeng Huang <huangyifeng@eswincomputing.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Troy Mitchell <troy.mitchell@linux.dev>
Tested-by: Marcel Ziswiler <marcel@ziswiler.com> # ebc77
Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>