Added vp8_dequant_idct_add_y_block_sse2 setup

In Change I83202ffd, I deleted one too many lines.

Change-Id: If05d7c8988eb5c00898dc7c833ad7d99b5eb23e7

vp8/decoder/x86/x86_dsystemdependent.c

@@ -50,6 +50,7 @@ void vp8_arch_x86_decode_init(VP8D_COMP *pbi)
 #if HAVE_SSE2
     if (flags & HAS_SSE2)
     {
+        pbi->dequant.idct_add_y_block    = vp8_dequant_idct_add_y_block_sse2;
         pbi->dequant.idct_add_uv_block   = vp8_dequant_idct_add_uv_block_sse2;
     }
 #endif