avcodec/cbs_h2645: Fix potential out-of-bounds array access

The maximum allowed index for an array access is FF_ARRAY_ELEMS - 1; yet
the current code allowed FF_ARRAY_ELEMS. This wasn't dangerous in practice,
as parameter sets with invalid ids were already filtered out during
reading.

Found via PVS-Studio (see ticket #8156).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit f3333c3c67)
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/cbs_h2645.c

@@ -666,7 +666,7 @@ static int cbs_h26 ## h26n ## _replace_ ## ps_var(CodedBitstreamContext *ctx, \
 { \
     CodedBitstreamH26 ## h26n ## Context *priv = ctx->priv_data; \
     unsigned int id = ps_var->id_element; \
-    if (id > FF_ARRAY_ELEMS(priv->ps_var)) { \
+    if (id >= FF_ARRAY_ELEMS(priv->ps_var)) { \
         av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid " #ps_name \
                " id : %d.\n", id); \
         return AVERROR_INVALIDDATA; \