qat.4: Cleanup

+ copyright symbols do not belong in Nd's (apropos results)
+ move hardware to HARDWARE for inclusion in the hw release notes
+ improve sysctls
+ lines which say nothing removed
+ links moved to see also
+ spacing and markup corrections

MFC after: 3 days
Reviewed by: markj, mhorne
Approved by: mhorne (mentor)
Approved by: re (cperciva)
Differential Revision: https://reviews.freebsd.org/D50381

(cherry picked from commit c1d9b2c9b03cade19cb4f94d3e29fba7179ac11a)
(cherry picked from commit 802edf23079388447659136805d97b95b0f90899)