vhost-vdpa: add uAPI for logging

virt inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I86ITO



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These new ioctl add support for setting bitmaps config,
like base address and buffer size from userspace.

When setup migration, VMM will call VHOST_SET_LOG_BASE and
VHOST_SET_LOG_SIZE to set address and size of buffer used
for storing bitmaps.

Then VMM start live migration, VMM will enable logging
vhost device by set feature VHOST_F_LOG_ALL.

And during live migration iterate, VMM get dirty page info
from vhost device by calling VHOST_LOG_SYNC.

Signed-off-by: jiangdongxu <jiangdongxu1@huawei.com>