mac_via: Fix to realize "mos6522-q800-via*" devices

mac_via: Fix to realize "mos6522-q800-via*" devices

mac_via_realize() creates a "mos6522-q800-via1" and a
"mos6522-q800-via2" device, but neglects to realize them.  Affects
machine q800.

In theory, a device becomes real only on realize.  In practice, the
transition from unreal to real is a fuzzy one.  The work to make a
device real can be spread between realize methods (fine),
instance_init methods (wrong), and board code wiring up the device
(fine as long as it effectively happens on realize).  Depending on
what exactly is done where, a device can work even when we neglect
to realize it.

These two appear to work.  Nevertheless, it's a clear misuse of the
interface.  Even when it works today (more or less by chance), it can
break tomorrow.

Fix by realizing them right away.

Fixes: 6dca62a0000f95e0b7020aa00d0ca9b2c421f341
Cc: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20200609122339.937862-9-armbru@redhat.com>
Tested-by: Laurent Vivier <laurent@vivier.eu>
Acked-by: Laurent Vivier <laurent@vivier.eu>