Bug fix: Issue 531:	MMX code tries to read from SSE2 register

Reported by Krzysztof Kaspruk.
https://code.google.com/p/webm/issues/detail?id=531

Change-Id: Ib5d5878ad07707bd42c2ca833eb021004f537012

vp8/common/x86/postproc_mmx.asm

diff --git a/vp8/common/x86/postproc_mmx.asm b/vp8/common/x86/postproc_mmx.asm
index 966c586..5cf110b 100644
--- a/vp8/common/x86/postproc_mmx.asm
+++ b/vp8/common/x86/postproc_mmx.asm
@@ -61,7 +61,7 @@
             mov         rcx,        8
 .init_borderd                                                    ; initialize borders
             lea         rdi,        [rdi + rax]
-            movq        [rdi],      xmm1
+            movq        [rdi],      mm1
 
             dec         rcx
             jne         .init_borderd
@@ -193,7 +193,6 @@
             movq        mm4,        [sym(vp8_rv) + rcx*2]
 %endif
             paddw       mm1,        mm4
-            ;paddw     xmm1,       eight8s
             psraw       mm1,        4
 
             packuswb    mm1,        mm0