In Memoriam: Hans Peter Selasky: Fix commit date

Memoriam dates should be in the format:
(start of commit bit - end of commit bit; RIP date deceased)

Fixes: b7652065 (In Memoriam: Hans Petter Selasky)
Reported by: mckusick
Approved by: mhorne (mentor)
Differential Revision: https://reviews.freebsd.org/D49404