hw: Avoid use of QOM type name macros in VMStateDescriptions

The name field in a VMStateDescription is part of the migration state
versioning, so changing it will break migration.  It's therefore a
bad idea to use a QOM typename macro to initialize it, because in
general we're free to rename QOM types as part of code refactoring
and cleanup.  For the handful of devices that were doing this by
mistake, replace the QOM typenames with the corresponding literal
strings.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
[AF: Use TYPE_PVSCSI for TypeInfo instead]
Signed-off-by: Andreas Färber <afaerber@suse.de>
