[nrf fromtree] soc: nordic: Don't override offset when TF-m is enabled

When TF-m is enabled on 54L the ROM_START_OFFSET should
not be overridden, even if MCUboot is enabled.

Signed-off-by: Dag Erik Gjørvad <dag.erik.gjorvad@nordicsemi.no>
(cherry picked from commit 46d1934)

Author: degjorva

soc/nordic/nrf54l/Kconfig.defconfig

@@ -33,7 +33,7 @@ choice NULL_POINTER_EXCEPTION_DETECTION
 endchoice
 
 config ROM_START_OFFSET
-	default 0x800 if BOOTLOADER_MCUBOOT
+	default 0x800 if BOOTLOADER_MCUBOOT && !BUILD_WITH_TFM
 
 endif # ARM