remove bit position from description of SIP_* flags.

use AST_FORMAT_AUDIO_MASK instead of playing with AST_FORMAT_MAX_AUDIO
to determine audio formats.
There is a dubious use of AST_FORMAT_MAX_AUDIO in sip_request_call()
which surely needs fixing, namely: 
 
        /* mask request with some set of allowed formats.
         * XXX this needs to be fixed.
         * The original code uses AST_FORMAT_AUDIO_MASK, but it is
         * unclear what to use here. We have global_capabilities, which is
         * configured from sip.conf, and sip_tech.capabilities, which is
         * hardwired to all audio formats.
         */
 
The latter is possibly something to backport when fixed.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@77682 65c4cc65-6c06-0410-ace0-fbb531ad65f3