vpx: [loongson] fix bug in var_filter_block2d_bil_16x

Which cause failed case:
1. MMI/VpxSubpelVarianceTest.Ref/6
2. MMI/VpxSubpelVarianceTest.Ref/7
3. MMI/VpxSubpelVarianceTest.ExtremeRef/6
4. MMI/VpxSubpelVarianceTest.ExtremeRef/7

Change-Id: I122ca20089e14ac324edd61295cf8f506e06afc8

vpx_dsp/mips/variance_mmi.c

@@ -1068,14 +1068,14 @@ static inline void var_filter_block2d_bil_16x(const uint8_t *a, int a_stride,
 
     "1:                                                         \n\t"
     MMI_ADDU(%[a], %[a], %[a_stride])
-    VAR_FILTER_BLOCK2D_BIL_FIRST_PASS_16_A
+    VAR_FILTER_BLOCK2D_BIL_FIRST_PASS_16_B
     MMI_ADDIU(%[temp2_ptr], %[temp2_ptr], 0x10)
-    VAR_FILTER_BLOCK2D_BIL_SECOND_PASS_16_B
+    VAR_FILTER_BLOCK2D_BIL_SECOND_PASS_16_A
 
     MMI_ADDU(%[a], %[a], %[a_stride])
-    VAR_FILTER_BLOCK2D_BIL_FIRST_PASS_16_B
+    VAR_FILTER_BLOCK2D_BIL_FIRST_PASS_16_A
     MMI_ADDIU(%[temp2_ptr], %[temp2_ptr], 0x10)
-    VAR_FILTER_BLOCK2D_BIL_SECOND_PASS_16_A
+    VAR_FILTER_BLOCK2D_BIL_SECOND_PASS_16_B
     "addiu      %[counter], %[counter],     -0x01               \n\t"
     "bnez       %[counter], 1b                                  \n\t"
     : [ftmp0] "=&f"(ftmp[0]), [ftmp1] "=&f"(ftmp[1]), [ftmp2] "=&f"(ftmp[2]),