PJSIP: Remove premature write of raw formats

Currently, there are situations that can occur when using chan_pjsip
and certain dialplan applications (notably ChanSpy()) that can cause
the channel to get no audio with scrolling warnings about format
mismatches. This is caused by a failure to update translation paths on
a mid-call native format update since the raw formats have already
been updated by res_pjsip_sdp_rtp.c in set_caps(). Removing the
premature raw format updates allows the translation paths to be setup
correctly and the raw read and write formats with them.

AFS-63 #close


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@415342 f38db490-d61c-443f-a65b-d21fe96a405b