[PATCH v3] watchdog: s3c2410: Fix potential deadlock on &wdt->lock

[Chengfeng Ye]

> I am sure you know what you changed in each version of your patches. I don't.
> Please provide change logs when you send new versions of your patches.

No problem, this is the change log for this patch.
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Changes in v3:
- Also use spin_lock_irqsave() in s3c2410wdt_keepalive().
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Changes in v2:
- Use function name instead of line number in the commit message.
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Best Regards,
Chengfeng