arm64: smccc: Reserve block of KVM "vendor" services for pKVM hypercalls

arm64: smccc: Reserve block of KVM "vendor" services for pKVM hypercalls

pKVM relies on hypercalls to expose services such as memory sharing to
protected guests. Tentatively allocate a block of 58 hypercalls (i.e.
fill the remaining space in the first 64 function IDs) for pKVM usage,
as future extensions such as pvIOMMU support, range-based memory sharing
and validation of assigned devices will require additional services.

Suggested-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/86a5h5yg5y.wl-maz@kernel.org
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240830130150.8568-8-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>