avcodec/dstdec: Replace AC overread check by sample rate check

Real files do skip coding 0 bits at the end, thus this kind of check
does not work reliable.

Fixes: Ticket 8770
Fixes: dst-256fs44-6ch-refdstencoder.dff

The samplerate is specified in ISO/IEC 14496-3:2005(E) as one of 3 fixed
values, this also can be used to limit the duration and avoid the timeout

This reverts commit f6df99db.

(cherry picked from commit 1679f23b)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>