sysutils/iocell: enable more architectures & handle new BSD grep

While iocell is a shell script and can work cross-platform, its evident
that nobody has actually tried to use it on anything other than amd64.

Use tighter egrep(1) invocations, that match the new default BSD grep
now in 13.0+ and up.

Approved by: maintainer timeout
Tested by: linimon
PR: 253703
Differential Revision: https://reviews.freebsd.org/D28004