swresample/swresample: do not reset tsf on swr_alloc_set_opts

so tsf option in aresample will have effect
previously tsf/internal_sample_format had no effect

fate is updated
s32p previously used fltp internally
dblp previously used fltp/dblp internally

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Muhammad Faiz <mfcc64@gmail.com>