[nrf fromtree] samples: boards: nrf: clock_control: Add memory-regions prop to uart sample

Add missing "memory-regions" property which is required for UART
on NRF54H20 to clock_control sample overlay file.

Signed-off-by: Michał Bainczyk <[email protected]>
(cherry picked from commit ba3662a)

Author: mib1-nordic

samples/boards/nordic/clock_control/configs/uart135.overlay

@@ -12,4 +12,5 @@
 
 &uart135 {
 	status = "okay";
+	memory-regions = <&cpuapp_dma_region>;
 };