avcodec/x86/vp9dsp_init_16bpp: Fix linking to missing ff_vp9_ipred_dr_32x32_16_avx2() on 32bit

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/x86/vp9dsp_init_16bpp.c

@@ -140,7 +140,9 @@ av_cold void ff_vp9dsp_init_16bpp_x86(VP9DSPContext *dsp)
         init_ipred_func(dl, DIAG_DOWN_LEFT, 16, 16, avx2);
         init_ipred_func(dl, DIAG_DOWN_LEFT, 32, 16, avx2);
         init_ipred_func(dr, DIAG_DOWN_RIGHT, 16, 16, avx2);
+#if ARCH_X86_64
         init_ipred_func(dr, DIAG_DOWN_RIGHT, 32, 16, avx2);
+#endif
     }
 
 #endif /* HAVE_X86ASM */