Remove unneeded if(params) checks in reqresp_parser.

Nick Lewis added them in https://reviewboard.asterisk.org/r/549/diff/1-2/
for no apparent reason. There is no way that params could become NULL in
that piece of code, so I removed these excess checks again.
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Merged revisions 344837 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 344839 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@344840 65c4cc65-6c06-0410-ace0-fbb531ad65f3