net/ntp: Reverse "Disable ntpd stack gap"

120137c822c9697c19cf94461f436f8ccc372d24 (svn r517694) disabled ntpd
ASLR stack gap, which caused ntpd to segfault. (The patch in
120137c822c9697c19cf94461f436f8ccc372d24 was subsequently submitted
to nwtime.org for inclusion into upstream ntp.) src commit
889b56c8cd84c9a9f2d9e3b019c154d6f14d9021 addressed the underlying cause
for the setrlimit segfault negating the need for this workaround. This
commit removes the workaround.

MFH: 2021Q4 (after a month)