hyperv: Add definitions for root partition driver to hv headers

hyperv: Add definitions for root partition driver to hv headers

A few additional definitions are required for the mshv driver code
(to follow). Introduce those here and clean up a little bit while
at it.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Link: https://lore.kernel.org/r/1741980536-3865-10-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1741980536-3865-10-git-send-email-nunodasneves@linux.microsoft.com>