zephyr: boards: Remove CONFIG_FPROTECT from nrf54l15

CONFIG_FPROTECT is defined only in NRF repository, it
should not be added here.

Signed-off-by: Grzegorz Chwierut <grzegorz.chwierut@nordicsemi.no>
diff --git a/boot/zephyr/boards/nrf54l15pdk_nrf54l15_cpuapp.conf b/boot/zephyr/boards/nrf54l15pdk_nrf54l15_cpuapp.conf
index 59a5491..33e7e61 100644
--- a/boot/zephyr/boards/nrf54l15pdk_nrf54l15_cpuapp.conf
+++ b/boot/zephyr/boards/nrf54l15pdk_nrf54l15_cpuapp.conf
@@ -7,6 +7,4 @@
 # Ensure that the qspi driver is disabled by default
 CONFIG_NORDIC_QSPI_NOR=n
 
-# TODO: below are not yet supported and need fixing
-CONFIG_FPROTECT=n
 CONFIG_BOOT_WATCHDOG_FEED=n