dts: bindings: Add fixed-clock DTS binding
dts: bindings: Add fixed-clock DTS binding

This commit adds binding for clock provider with fixed frequency.

Signed-off-by: Derek Hageman <682606ea76a35bfea4caa12867716a4382b059a9@inthat.cloud>
Signed-off-by: Piotr Zięcik <9ef3595b5f0f4fa8d0ceeb52cc0cf0411a0684dd@nordicsemi.no>

galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr