arm64: dts: imx93-kontron: update heartbeat gpio

A wrong GPIO was specified in Linux device tree for heartbeat on iMX93. Adjusted the configuration, so now this LED started to work.

U-Boot MR: u-boot!50 (closed)

assigned to @mvaniulin

mentioned in merge request u-boot!50 (closed)

changed the description

changed the description

requested review from @fschrempf

This change is now part of !155 (closed).

closed