ivas_omasa_com functions converted to fixed point.

[x] Below functions present in ivas_omasa_com file are converted
to fixed point.
ivas_omasa_ism_mode_select
ivas_set_omasa_TC
ivas_interformat_brate
ivas_combined_format_brate_sanity
bits_index_ism_ratio
calculate_nbits_meta
ivas_get_stereo_panning_gains - does not get hit by any test stream,
test is done through unit testing.