devel/rubygem-devise: fix PR 200625 correctly

This reverts r388685 and modifies the gemspec to not include a file that
caused the offending html file to get generated in the rdoc step.

Bump portrevision because now the rails dependencies are getting pulled
in correctly again.

PR: 200625
Differential Revision: https://reviews.freebsd.org/D2739
Approved by: mat (mentor)