tools: hv: Add vmbus_bufring

Common userspace interface for read/write from VMBus ringbuffer.
This implementation is open for use by any userspace driver or
application seeking direct control over VMBus ring buffers.
A significant  part of this code is borrowed from DPDK.
Link: https://github.com/DPDK/dpdk/



Currently this library is not supported for ARM64.

Signed-off-by: Mary Hardy <maryhardy@microsoft.com>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Link: https://lore.kernel.org/r/1711788723-8593-5-git-send-email-ssengar@linux.microsoft.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>