Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages

Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages

[ Upstream commit a5ddb74588213c31ce993a8e9a09d1ffdc11a142 ]

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary.  Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove the code to create and manage the second
mapping for VMBus monitor pages. Because set_memory_decrypted()
and set_memory_encrypted() are no-ops in normal VMs, it's
not even necessary to test for being in a Confidential VM
(a.k.a., "Isolation VM").

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/1679838727-87310-9-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Stable-dep-of: 09eea7ad0b8e ("Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary")
Signed-off-by: Sasha Levin <sashal@kernel.org>