soc: nordic: Select new nrf54lx compatible kconfig option

Select the newly introduced nrf54lx compatible kconfig
option.

This is common both for real HW and for simulated HW,
allowing SW to behave appropriately for both.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>