machine: Replace has_dynamic_sysbus with list of allowed devices

machine: Replace has_dynamic_sysbus with list of allowed devices

The existing has_dynamic_sysbus flag makes the machine accept
every user-creatable sysbus device type on the command-line.
Replace it with a list of allowed device types, so machines can
easily accept some sysbus devices while rejecting others.

To keep exactly the same behavior as before, the existing
has_dynamic_sysbus=true assignments are replaced with a
TYPE_SYS_BUS_DEVICE entry on the allowed list.  Other patches
will replace the TYPE_SYS_BUS_DEVICE entries with more specific
lists of devices.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: qemu-arm@nongnu.org
Cc: qemu-ppc@nongnu.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20171125151610.20547-2-ehabkost@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>