Revert "[nrf noup] boards/nordic/nrf54l15dk: Set ROM offset by PM"

This reverts commit 2b3a0c6.

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

boards/nordic/nrf54l15dk/Kconfig.defconfig

@@ -8,7 +8,6 @@ if BOARD_NRF54L15DK_NRF54L05_CPUAPP || BOARD_NRF54L15DK_NRF54L10_CPUAPP || \
 	BOARD_NRF54L15DK_NRF54L15_CPUAPP
 
 config ROM_START_OFFSET
-	default 0 if PARTITION_MANAGER_ENABLED
 	default 0x800 if BOOTLOADER_MCUBOOT
 
 endif # BOARD_NRF54L15DK_NRF54L05_CPUAPP || BOARD_NRF54L15DK_NRF54L10_CPUAPP || \