Drivers: hv: vmbus: Mark vmbus ring buffer visible to host in Isolation VM

Mark vmbus ring buffer visible with set_memory_decrypted() when
establish gpadl handle.

Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20211025122116.264793-5-ltykernel@gmail.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>