avfilter/x86/vf_pullup: try to fix build on x64

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/x86/vf_pullup.asm

@@ -57,7 +57,7 @@ cglobal pullup_filter_diff, 3, 5, 8, first, second, size
     movd      eax, m3
     psrlq      m3, 32
     movd       r4, m3
-    add       eax, r4
+    add       eax, r4d
     RET
 
 INIT_MMX mmx
@@ -136,7 +136,7 @@ cglobal pullup_filter_comb, 3, 5, 8, first, second, size
     movd      eax, m5
     psrlq      m5, 32
     movd       r4, m5
-    add       eax, r4
+    add       eax, r4d
     RET
 
 INIT_MMX mmx
@@ -173,6 +173,6 @@ cglobal pullup_filter_var, 3, 5, 8, first, second, size
     movd      eax, m3
     psrlq      m3, 32
     movd       r4, m3
-    add       eax, r4
+    add       eax, r4d
     shl       eax, 2
     RET