The 'host' CPU model isn't available until KVM or HVF is enabled.
For example, the following error messages are seen when the guest
is started with option '-cpu cortex-a8' on tcg.
ERROR:../hw/core/machine.c:1423:is_cpu_type_supported: \
assertion failed: (model != NULL)
Bail out! ERROR:../hw/core/machine.c:1423:is_cpu_type_supported: \
assertion failed: (model != NULL)
Aborted (core dumped)
Hide 'host' CPU model until KVM or HVF is enabled. With this applied,
the valid CPU models can be shown.
qemu-system-aarch64: Invalid CPU type: cortex-a8
The valid types are: cortex-a7, cortex-a15, cortex-a35, \
cortex-a55, cortex-a72, cortex-a76, cortex-a710, a64fx, \
neoverse-n1, neoverse-v1, neoverse-n2, cortex-a53, \
cortex-a57, max
Signed-off-by: Gavin Shan <gshan@redhat.com>