res_format_attr_h264: Fix crash when determining joint capability.

The res_format_attr_h264 module currently incorrectly attempts to
copy SPS and PPS information from the wrong attribute. This change
fixes that.

ASTERISK-24616 #close
Reported by: Yura Kocyuba

Review: https://reviewboard.asterisk.org/r/4392/
........

Merged revisions 431521 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@431522 65c4cc65-6c06-0410-ace0-fbb531ad65f3