soc: nordic: nrf53: assign pin xl1,xl2 to app core if lfxo disabled

Fixes zephyrproject-rtos/zephyr#92663

Disabled LFXO via devicetree allows pin 0.00 and 0.01 to work correctly
as gpio by assigning it to the app core instead of peripheral. Removed
deprecated Kconfig options so DT is the only config path now.

Signed-off-by: Ivynya Lu <ivy.lu@level.co>