KVM: arm64: Handle FFA_MEM_LEND calls from the host

Handle FFA_MEM_LEND calls from the host by treating them identically to
FFA_MEM_SHARE calls for the purposes of the host stage-2 page-table, but
forwarding on the original request to EL3.

Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230523101828.7328-9-will@kernel.org


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>