Additional register waits in MM engines on Vega10

[Christian König]

Hi guys,

The *_vm_flush functions on Vega10 insert an extra register wait before writing to the request register.

That doesn't looks like it makes any sense to me and I think it is just a leftover from bringup.

Now it's in the way of cleaning up the *_vm_flush functions into something common. So can we remove it?

Thanks,
Christian.