build: add gpio configuration for nrf54l15

[RobertGalatNordic]

allows to initialize FSK/LoRa, but still does not work

CI parameters

(branch, hash, pull/XXX/head)
NRF_revision=main

(true, false)
Create_NRF_PR=true

Description

JIRA ticket: KRKNWK-18781

Detail description of the change

Self review

• There is no commented code.
• There are no TODO/FIXME comments without associated issue ticket.
• Commits are properly organized
• Verification
  • Unit tests were updated to include the change.
  • Change has been tested.

[github-actions]

Sample		diff	used	total
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.dut	RAM	15.3 KB	136.65 KB	256 KB
	ROM	78.75 KB	493.64 KB	730 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.hello	RAM	15.23 KB	102.97 KB	256 KB
	ROM	78.53 KB	429.46 KB	730 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.hello.ble_only	RAM	0 B	87.74 KB	256 KB
	ROM	-1.02 KB	349.66 KB	730 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.hello.ble_only.release	RAM	0 B	82.89 KB	256 KB
	ROM	-240 B	285.64 KB	730 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.hello.no_dfu	RAM	0 B	74.47 KB	256 KB
	ROM	-1.36 KB	330.82 KB	1.48 MB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.hello.release	RAM	0 B	82.89 KB	256 KB
	ROM	-240 B	285.77 KB	730 KB
nrf52840dk_nrf52840:sample.sidewalk.demo	RAM	0 B	119.83 KB	256 KB
	ROM	16 B	495.29 KB	983.5 KB
nrf52840dk_nrf52840:sample.sidewalk.dut	RAM	0 B	143.21 KB	256 KB
	ROM	16 B	554.2 KB	983.5 KB
nrf52840dk_nrf52840:sample.sidewalk.hello	RAM	0 B	109.58 KB	256 KB
	ROM	16 B	494.99 KB	983.5 KB
nrf52840dk_nrf52840:sample.sidewalk.hello.no_dfu	RAM	0 B	96.29 KB	256 KB
	ROM	16 B	477.19 KB	983.5 KB
nrf52840dk_nrf52840:sample.sidewalk.hello.release	RAM	0 B	104.71 KB	256 KB
	ROM	16 B	430.07 KB	983.5 KB
nrf5340dk_nrf5340_cpuapp:sample.sidewalk.demo	RAM	0 B	108.09 KB	440 KB
	ROM	16 B	433.12 KB	975.5 KB
nrf5340dk_nrf5340_cpuapp:sample.sidewalk.dut	RAM	0 B	131.55 KB	440 KB
	ROM	16 B	492.07 KB	975.5 KB
nrf5340dk_nrf5340_cpuapp:sample.sidewalk.hello	RAM	0 B	98.18 KB	440 KB
	ROM	16 B	432.9 KB	975.5 KB
nrf5340dk_nrf5340_cpuapp:sample.sidewalk.hello.no_dfu	RAM	0 B	84.95 KB	440 KB
	ROM	16 B	414.95 KB	975.5 KB
nrf5340dk_nrf5340_cpuapp:sample.sidewalk.hello.release	RAM	0 B	93.46 KB	440 KB
	ROM	16 B	365.93 KB	975.5 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.demo	RAM	15.23 KB	112.92 KB	256 KB
	ROM	78.34 KB	429.79 KB	730 KB
nrf54l15pdk_nrf54l15_cpuapp:sample.sidewalk.demo.ble_only	RAM	0 B	97.69 KB	256 KB
	ROM	-984 B	350.24 KB	730 KB