avcodec/proresenc_kostya: Remove harmful check

avcodec/proresenc_kostya: Remove harmful check

The ProRes encoder allocates huge worst-case buffers just to be safe;
and for huge resolutions (8k in this case) these can be so big that the
number of bits does no longer fit into a (signed 32-bit) int; this means
that one must no longer use the parts of the PutBits API that deal with
bit counters. Yet proresenc_kostya did it, namely for a check about
whether we are already beyond the end. Yet this check is unnecessary
nowadays, because the PutBits API comes with automatic checks (with
a log message and a av_assert2() in put_bits() and an av_assert0() in
flush_put_bits()), so this is unnecessary. So simply remove the check.

Fixes ticket #9173.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>