KVM: arm64: Forward safe PSCI SMCs coming from host

Forward the following PSCI SMCs issued by host to EL3 as they do not
require the hypervisor's intervention. This assumes that EL3 correctly
implements the PSCI specification.

Only function IDs implemented in Linux are included.

Where both 32-bit and 64-bit variants exist, it is assumed that the host
will always use the 64-bit variant.

 * SMCs that only return information about the system
   * PSCI_VERSION        - PSCI version implemented by EL3
   * PSCI_FEATURES       - optional features supported by EL3
   * AFFINITY_INFO       - power state of core/cluster
   * MIGRATE_INFO_TYPE   - whether Trusted OS can be migrated
   * MIGRATE_INFO_UP_CPU - resident core of Trusted OS
 * operations which do not affect the hypervisor
   * MIGRATE             - migrate Trusted OS to a different core
   * SET_SUSPEND_MODE    - toggle OS-initiated mode
 * system shutdown/reset
   * SYSTEM_OFF
   * SYSTEM_RESET
   * SYSTEM_RESET2

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-19-dbrazdil@google.com