Use common allocator for CharDriverState.
Rename the now untouched parent field.
The casts added are temporary, they are replaced with QOM type-safe
macros in a later patch in this series.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>