codec: mpeg_audio: fix pts update

Fixes #12722

(cherry picked from commit 72b03859fd8b715d9baeb5b378170d81517b01e8)

modules/codec/mpeg_audio.c

@@ -248,7 +248,7 @@ static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
             /* New frame, set the Presentation Time Stamp */
             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
             if( p_sys->i_pts > VLC_TS_INVALID &&
-                p_sys->i_pts != date_Get( &p_sys->end_date ) )
+                p_sys->i_pts > date_Get( &p_sys->end_date ) )
             {
                 date_Set( &p_sys->end_date, p_sys->i_pts );
             }