[PATHC v6] video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver

[Dexuan Cui]

> From: Wei Hu <weh at microsoft.com>
> Sent: Tuesday, September 17, 2019 11:03 PM
> [...]
> ---
>     v6: Do not request host refresh when the VM guest screen is
>     closed or minimized.

Looks good to me. Thanks!

Reviewed-by: Dexuan Cui <decui at microsoft.com>