dfa: remove redundant check

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dfa.c

@@ -254,8 +254,6 @@ static int decode_wdlt(GetByteContext *gb, uint8_t *frame, int width, int height
             y        += skip_lines;
             segments = bytestream2_get_le16(gb);
         }
-        if (frame_end <= frame)
-            return -1;
         if (segments & 0x8000) {
             frame[width - 1] = segments & 0xFF;
             segments = bytestream2_get_le16(gb);