[PATCH RESEND] dmaengine: milbeaut-hdmac: Fix potential deadlock on &mc->vc.lock

[Chengfeng Ye]

> while at it, maybe also use vc->lock, instead of mc->vc.lock here and
> in other two places, just like the rest of driver.

Thanks for the review, v2 patch is just sent to address the problem.

Thanks,
Chengfeng