Few fixed point converted functions included in call-stack

[x] stereo_dft_sg_recovery_fx,rc_uni_dec_init_fx,rc_uni_dec_read_symbol_fastS_fx
added in call-stack.
[x] Added fix for overflow occuring in rc_uni_dec_read_symbol_fastS_fx
[x] Added fix for overflow observed in stereo_dft_sg_recovery_fx