xen-block: Replace qdict_put_obj() by qdict_put() where appropriate

xen-block: Replace qdict_put_obj() by qdict_put() where appropriate

Patch created mechanically by rerunning:

    $ spatch --sp-file scripts/coccinelle/qobject.cocci \
             --macro-file scripts/cocci-macro-file.h \
             --dir hw/block --in-place

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190313174433.12966-1-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>