vhost: handle error while adding split ranges to iotlb

vhost_iotlb_add_range_ctx() handles the range [0, ULONG_MAX] by
splitting it into two ranges and adding them separately. The return
value of adding the first range to the iotlb is currently ignored.
Check the return value and bail out in case of an error.

Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Link: https://lore.kernel.org/r/20220312141121.4981-1-mail@anirudhrb.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: e2ae38cf ("vhost: fix hung thread due to erroneous iotlb entries")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>