hvf: Add Apple Silicon support

hvf: Add Apple Silicon support

With Apple Silicon available to the masses, it's a good time to add support
for driving its virtualization extensions from QEMU.

This patch adds all necessary architecture specific code to get basic VMs
working, including save/restore.

Known limitations:

  - WFI handling is missing (follows in later patch)
  - No watchpoint/breakpoint support

Signed-off-by: Alexander Graf <[email protected]>
Reviewed-by: Roman Bolshakov <[email protected]>
Reviewed-by: Sergio Lopez <[email protected]>
Reviewed-by: Peter Maydell <[email protected]>
Message-id: 20210916155404[email protected]
[PMM: added missing #include]
Signed-off-by: Peter Maydell <[email protected]>