cryptocheck: Be friendlier when testing software crypto backends

• Fail loudly if we can't change the kern.crypto.allow_soft sysctl.
• Add more drivers to the list.

MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D52490

(cherry picked from commit e63bf6aa523eb9a865b7ce34d01e75a13818b367)