[nrf fromtree] zephyr: Add NRF54L configuration

Adds default Kconfig configuration that allows to build MCUboot
for NRF54L.
Currently this configuration turns off WDT and FPROTECT,
which is TODO to fix.

Signed-off-by: Dominik Ermel <[email protected]>
Signed-off-by: Mateusz Michalek <[email protected]>
(cherry picked from commit 4b4cc85)
Signed-off-by: Andrzej Puzdrowski <[email protected]>

Author: michalek-no

boot/zephyr/boards/nrf54l15dk_nrf54l15_cpuapp.conf

@@ -0,0 +1,12 @@
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+CONFIG_BOOT_MAX_IMG_SECTORS=256
+
+# 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