[action] [PR:16612] [armhf][Nokia-7215] Enable Watchdog service

[mssonicbld]

Why I did it

Enable watchdog for Nokia 7215 platform

Work item tracking

• Microsoft ADO (number only): 24981141

How I did it

Implement service which arm's the watchdog and send keep alive every minute.
start service be default on boot up

How to verify it

Verify Watchdog is enabled on boot up:
"sudo systemctl status cpu_wdt.service" should show that service as active
admin@sonic:~$ sudo watchdogutil status
Status: Armed
Time remaining: 138 seconds

Stop Service and verify watchdog is disarmed:
admin@sonic:$ sudo systemctl stop cpu_wdt.service
admin@sonic:$ sudo watchdogutil status
Status: Unarmed

Logs added to notify service being armed/Disarmed and for every keep alive(every 55 seconds)

2430:2023-10-13T01:42:11.077639+00:00 sonic Watchdog: CPUWDT Enabled: watchdog armed=True
2988:Oct 13 01:43:06.132343 sonic INFO Watchdog: CPUWDT keepalive
11925:Oct 13 01:44:01.186558 sonic INFO Watchdog: CPUWDT keepalive
12418:Oct 13 01:44:56.240061 sonic INFO Watchdog: CPUWDT keepalive

47159:Oct 13 02:27:15.490356 sonic NOTICE Watchdog: CPUWDT Disabled: watchdog armed=False

Also verified OC test suits and created seperate PR to uptate sonic-mgmt
sonic-net/sonic-mgmt#10082

https://github.com/sonic-net/sonic-mgmt/blob/master/tests/platform_tests/api/test_watchdog.py
https://github.com/sonic-net/sonic-mgmt/blob/master/tests/common/helpers/platform_api/watchdog.py

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305

Tested branch (Please provide the tested image version)

Description for the changelog

Enable watchdog service for Nokia-7215 platform

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[mssonicbld]

Original PR: #16612