res_pjsip_phoneprov_provider: Revert 433996 / 433997.

res_pjsip_phoneprov_provider is using ao2_callback with OBJ_MULTIPLE, then
ignoring the return.  OBJ_NODATA flag was to prevent a reference leak, but
this caused the module to FRACK on unload.  Revert change until this can
be investigated further.

ASTERISK-24935
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4578/
........

Merged revisions 434025 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434026 65c4cc65-6c06-0410-ace0-fbb531ad65f3