mail/milter-greylist: minor fixes

- Use LIB_DEPS for curl, spf and geoip
- Use ${PORTSDIR} instead of {.CURDIR} for bsd.milter.mk location
- Do not bump PORTREVISION as all of curl, spf and geoip are disabled by defaul

PR:		193993
Submitted by:	Mikhail Tsatsenko <m.tsatsenko@gmail.com>
Approved by:	mentors (implicit)
Nuke some @dirrm from devel