changed ntpq -n -c readvar regex for compatability

\R was failing with ntp-4.2.2p1-15.el5.centos.1.x86_64 due to extra 0x0a printed at the end of ntpq -n -c "readvar xx srcadr"
ntp-4.2.4p8-3.el6.centos.x86_64 does not print the trailing 0x0a.