Remove useless code

Remove useless code
Since 
const uint8_t g_kuiMbNonZeroCountIdx[24] = {
  //  0   1 | 4  5      luma 8*8 block           non_zero_count[16+8]
  0,  1,  4,  5,   //  2   3 | 6  7        0  |  1                  0   1   2   3
  2,  3,  6,  7,   //---------------      ---------                 4   5   6   7
  8,  9, 12, 13,   //  8   9 | 12 13       2  |  3                  8   9  10  11
  10, 11, 14, 15,   // 10  11 | 14 15-----------------------------> 12  13  14  15
  16, 17, 20, 21,   //----------------    chroma 8*8 block          16  17  18  19
  18, 19, 22, 23   // 16  17 | 20 21        0    1                 20  21  22  23
}; //decoder
and
const uint8_t g_kuiMbCountScan4Idx[24] = {
  //  0   1 | 4  5      luma 8*8 block           pNonZeroCount[16+8]
  0,  1,  4,  5,   //  2   3 | 6  7        0  |  1                  0   1   2   3
  2,  3,  6,  7,   //---------------      ---------                 4   5   6   7
  8,  9, 12, 13,   //  8   9 | 12 13       2  |  3                  8   9  10  11
  10, 11, 14, 15,   // 10  11 | 14 15-----------------------------> 12  13  14  15
  16, 17, 20, 21,   //----------------    chroma 8*8 block          16  17  18  19
  18, 19, 22, 23   // 16  17 | 20 21        0    1                 20  21  22  23
}; //encoder
contains value 0~23, it is OK to remove these code.
Review:
https://rbcommons.com/s/OpenH264/r/390/