Make EQoS Ethernet to work

Make second Ethernet interface(EQoS) work

Out of the box, the EQoS Ethernet controller is not detected and initialized in U-Boot.

This problem was fixed by following:

• cherry-picked a commit from mainline U-Boot which adds support of iMX93 SoC to the DWC EQoS driver;
• actualized imx93-kontron-bl-osm-s-u-boot.dtsi according to this change;
• added an initialization routine for EQoS clock to the board file.