Use correct register size.

Fixes compilation with NASM.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavcodec/x86/rv34dsp.asm

@@ -59,7 +59,7 @@ cglobal rv34_idct_dc_add_mmx, 3, 3
     ; calculate DC
     IDCT_DC_ROUND r2
     pxor       m1, m1
-    movd       m0, r2
+    movd       m0, r2d
     psubw      m1, m0
     packuswb   m0, m0
     packuswb   m1, m1
@@ -96,7 +96,7 @@ cglobal rv34_idct_dc_add_sse4, 3, 3, 6
     pxor       m1, m1
 
     ; calculate DC
-    movd       m0, r2
+    movd       m0, r2d
     lea        r2, [r0+r1*2]
     movd       m2, [r0]
     movd       m3, [r0+r1]