Install pvscsi man page
This was lost during the initial introduction of the pvscsi driver [1].
Later the driver was enabled on arm64 [2], so also install the man page
on arm64.
- 052e12a5084f Add the pvscsi driver to the tree
- 375d797b8191 Enable pvscsi and vmx in arm64 GENERIC
Reviewed by: emaste, Alexander Ziaee <concussious.bugzilla_runbox.com> (manpages)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D47712
(cherry picked from commit 1811fa623d74b42f79c109c3fe8ea9dd21d60076)