- Use _mm_loadl_epi64 instead of _mm_loadu_si128 for
  uint16_t temp2[4 * 4] buffer.
- Refer to:
  d0de89a1 remove vpx_highbd_1[02]_sub_pixel_variance4x4_sse4_1
BUG=webm:1242

Change-Id: Ieff555c8dd8070937f27f4ec8535b77e1ed5b8b2