Make the options for the general and profiles more consistent

for the "pls_hold_prompt" option. This does not affect any released
version of Asterisk, so there is no need to update the CHANGES
file for this.

(closes issue #13893)
Reported by: eliel



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@159250 65c4cc65-6c06-0410-ace0-fbb531ad65f3