kldstat.8: Polish options

+ Align and alphabetize options
+ -q: s/Only/Quietly/ for search
+ Tag SPDX

MFC after: 3 days
Reviewed by: gbe, carlavilla, mhorne
Approved by: carlavilla, mhorne (mentors)
Differential Revision: https://reviews.freebsd.org/D48325

(cherry picked from commit 8d5d97372361aadb3d6cdfc5f5d1f8edcaa825aa)