avcodec/hevc/ps: use unsigned shift

Fixes: left shift of 1 by 31 places cannot be represented in type 'int'
Fixes: 70726/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HEVC_fuzzer-6149928703819776

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/hevc/ps.c

@@ -1101,7 +1101,7 @@ int ff_hevc_parse_sps(HEVCSPS *sps, GetBitContext *gb, unsigned int *sps_id,
         sps->used_by_curr_pic_lt = 0;
         for (i = 0; i < sps->num_long_term_ref_pics_sps; i++) {
             sps->lt_ref_pic_poc_lsb_sps[i]       = get_bits(gb, sps->log2_max_poc_lsb);
-            sps->used_by_curr_pic_lt            |= get_bits1(gb) * (1 << i);
+            sps->used_by_curr_pic_lt            |= get_bits1(gb) << i;
         }
     }