vhost_iotlb: split out IOTLB initialization

mainline inclusion
from mainline-v5.19-rc1
commit 1cb10899
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1cb108994c6830cc6a6e066ad7d9a22ef59fa167



----------------------------------------------------------------------

This patch splits out IOTLB initialization to make sure it could be
reused by external modules.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-9-gdawar@xilinx.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Pengyuan Zhao <zhaopengyuan@hisilicon.com>