hyperv: Enable the hypercall output page for the VTL mode

Due to the hypercall page not being allocated in the VTL mode,
the code resorts to using a part of the input page.

Allocate the hypercall output page in the VTL mode thus enabling
it to use it for output and share code with dom0.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250108222138.1623703-4-romank@linux.microsoft.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250108222138.1623703-4-romank@linux.microsoft.com>