dsp.c ast_dsp_call_progress use local short variable in loop, plus other cleanup

janitor cleanup. No functional change.

1). ast_dsp_call_progress: use 'short samp' instead of s[x] inside loop.
    apply same casting as other _init, dsp->energy = (int32_t) samp * (int32_t) samp

2). ast_dtmf_detect_init: move repeated setting of s->energy to outside of loop.
    do goertzel_init loop first before setting s->lasthit and s->current_hit, consistant with ast_dsp_digitreset()

3). ast_mf_detect_init:
    do goertzel_init loop first before setting s->hits[] and s->current_hit, consistant with ast_dsp_digitreset()

4). Don't chain init different variables, as the type may change

Review https://reviewboard.asterisk.org/r/2107/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@373275 65c4cc65-6c06-0410-ace0-fbb531ad65f3