Fix UEFI manpage whitespace and minor issues

Submitted by:	wblock
MFC after:	4 days
Differential Revision: https://reviews.freebsd.org/D959


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273235 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f