Fix duplicate Odin 3 headphones UCM section

[bernhardberger]

Summary

• remove the second duplicate SectionDevice."Headphones" block from the Odin 3 UCM profile
• retain the headphone definition routed to hw:${CardId},1; the removed copy incorrectly reused speaker PCM hw:${CardId},0
• add a regression test that rejects duplicate named device, use-case, and modifier sections in shipped UCM files

Context

The duplicate was inherited from AYN's SM8750 UCM contribution. Both blocks declare the same UCM device identifier, but point at different PCMs.

This malformed profile may contribute to #120. I have Odin 3 hardware, but it is not currently running Armada, so I could not verify jack detection or routing with this change. This PR therefore references rather than closes that issue; insertion/removal, automatic speaker mute, and headphone playback still need validation on-device under Armada.

Testing

• regression test failed on the original profile and identified lines 29/48
• bash tests/alsa-ucm-duplicates-test.sh
• complete tests/*-test.sh loop
• shfmt --diff tests/alsa-ucm-duplicates-test.sh
• git diff --check

just and shellcheck were not available in the local environment.