[nrf fromlist] soc: nordic: nrf54h: Enable use of RTT on cpuapp

RTT need to use RAM which is not cacheable as RTT does not support
data cache. Using cpuapp TCM RAM memory section for RTT.

Upstream PR #: 100570

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp.dts

@@ -45,6 +45,7 @@
 		watchdog0 = &wdt010;
 		mcuboot-button0 = &button0;
 		mcuboot-led0 = &led0;
+		rtt-custom-section = &cpuapp_tcm_region;
 	};
 
 	buttons {

soc/nordic/nrf54h/Kconfig.defconfig.nrf54h20_cpuapp

@@ -17,4 +17,8 @@ config POWER_DOMAIN
 config CODE_DATA_RELOCATION
 	default y if (PM || POWEROFF) && !MCUBOOT
 
+choice SEGGER_RTT_SECTION
+	default SEGGER_RTT_SECTION_CUSTOM_DTS_REGION
+endchoice
+
 endif # SOC_NRF54H20_CPUAPP