Allow lists for "nooption" and "nooptions" keywords.

usr.sbin/config/config.y
According to config(5), the "device", "devices",
"nodevice", "nodevices", "option", "options",
"nooption", and "nooptions" keywords can all take a
comma-separated list of values. However, the yacc code
did not allow lists for "nooption" and "nooptions", only
single values. This commit fixes the yacc code to allow
comma separated values for all the above keywords.

Submitted by: asomers
MFC after: 1 week
Sponsored by: Spectra Logic
MFSpectraBSD: 1095296 on 2014/10/07