[14.5-stable] pkg/debug: fix COM port detection

[christoph-zededa]

Description

Based on #5876

Newer kernels no longer expose /sys/class/tty//device/resources. Switch to reading port and IRQ directly from the per-tty sysfs files /sys/class/tty//port and /sys/class/tty/*/irq.

On x86_64, a port value of 0x0 indicates no hardware is present and the entry is skipped. The IO port range is computed as base to base+7 to match the standard 8-byte UART register window.

Qemu tests:
Effect on EVE master:
4 COM ports are detected, instead of 0

Effect on EVE 14.5:
4 COM ports are detected, instead of 1
This is because the serial port connected via PCI was detected, but not the ones via uart8250.

[debug] root@linuxkit-525400123456:~$ ls -l /sys/class/tty/ | grep ttyS
lrwxrwxrwx    1 root     root             0 Apr 28 10:14 ttyS0 -> ../../devices/pnp0/00:03/tty/ttyS0
lrwxrwxrwx    1 root     root             0 Apr 28 10:14 ttyS1 -> ../../devices/platform/serial8250/tty/ttyS1
lrwxrwxrwx    1 root     root             0 Apr 28 10:14 ttyS2 -> ../../devices/platform/serial8250/tty/ttyS2
lrwxrwxrwx    1 root     root             0 Apr 28 10:14 ttyS3 -> ../../devices/platform/serial8250/tty/ttyS3

How to test and validate this PR

Run spec.sh and check that all COM ports are printed.

Changelog notes

Fix COM port detection in spec.sh

Also, to the PRs that should be backported into any stable branch, please
add a label stable.

Checklist

• I've provided a proper description
• I've added the proper documentation
• I've tested my PR on amd64 device
• I've tested my PR on arm64 device
• I've written the test verification instructions
• I've set the proper labels to this PR

For backport PRs (remove it if it's not a backport):

• I've added a reference link to the original PR
• PR's title follows the template

And the last but not least:

• I've checked the boxes above, or I've provided a good reason why I didn't
  check them.

Please, check the boxes above after submitting the PR in interactive mode.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 32.62%. Comparing base (272ffae) to head (584d2ec).
⚠️ Report is 126 commits behind head on 14.5-stable.

Additional details and impacted files

@@               Coverage Diff               @@
##           14.5-stable    #5890      +/-   ##
===============================================
+ Coverage        24.97%   32.62%   +7.64%     
===============================================
  Files                8        9       +1     
  Lines             1185     1122      -63     
===============================================
+ Hits               296      366      +70     
+ Misses             820      675     -145     
- Partials            69       81      +12     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.