Drivers: hv: utils: Invoke the poll function after handshake

Drivers: hv: utils: Invoke the poll function after handshake

commit 2d0c3b5ad739697a68dc8a444f5b9f4817cf8f8f upstream.

When the handshake with daemon is complete, we should poll the channel since
during the handshake, we will not be processing any messages. This is a
potential bug if the host is waiting for a response from the guest.
I would like to thank Dexuan for pointing this out.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>