Fix av1_iht8x4_32_add_sse2() implementation

Fix the 8x4 inverse transform for ADST row process.

Change-Id: Iceff4ab356a51218a952b53b1134606548832eac

av1/common/x86/idct_intrin_sse2.c

diff --git a/av1/common/x86/idct_intrin_sse2.c b/av1/common/x86/idct_intrin_sse2.c
index 828ed67..62c2731 100644
--- a/av1/common/x86/idct_intrin_sse2.c
+++ b/av1/common/x86/idct_intrin_sse2.c
@@ -1013,7 +1013,7 @@
       aom_idct8_sse2(in);
       break;
     case DCT_ADST:
-    case ADST_ADST:
+    case ADST_ADST: aom_iadst8_sse2(in); break;
 #if CONFIG_EXT_TX
     case DCT_FLIPADST:
     case FLIPADST_FLIPADST: