lxd/instance/drivers: Restrict CPU hotplugging
lxd/instance/drivers: Restrict CPU hotplugging

This restricts CPU hotplugging to supported architectures only.

Signed-off-by: Thomas Hipp <5f82c492b3b00e427412d216ce820707a10c51ce@canonical.com>

lxc/lxd,lxc/lxd,lxc/lxd,lxc/lxd,lxc/lxd,lxc/lxd,lxc/lxd