soc: arm: eos_s3: Use frequency from Kconfig to configure main clock
soc: arm: eos_s3: Use frequency from Kconfig to configure main clock

Allows applications to use other frequencies than 60 MHz.
For example 48 MHz for USB communication with usbserial driver.

Signed-off-by: Michal Sieron <efb49a7c59124393d61f00761aa9acfb90220a86@antmicro.com>

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