capsicum_helpers: Add FIODTYPE to default ioctls allowed

FIODTYPE will be needed by hexdump(1) to speed up the -s flag on devices
that should be able to support fseek(3); specifically, in an attempt to
correct for the fact that most tape drives don't support seeking yet don't
indicate as such when fseeko(3) is invoked. Related: D10939

Reviewed by: cem, emaste, oshogbo
Approved by: emaste (mentor)
Differential Revision: https://reviews.freebsd.org/D10937