Revert "[nrf noup] soc: nordic: nrf54l: Add ROM start offset PM override"

This reverts commit bc38fb0.

Signed-off-by: Dag Erik Gjørvad <dag.erik.gjorvad@nordicsemi.no>

Author: degjorva

soc/nordic/nrf54l/Kconfig.defconfig

@@ -33,7 +33,6 @@ choice NULL_POINTER_EXCEPTION_DETECTION
 endchoice
 
 config ROM_START_OFFSET
-	default 0 if PARTITION_MANAGER_ENABLED
 	default 0x800 if BOOTLOADER_MCUBOOT
 
 endif # ARM