Add : for a label in asm code

Change-Id: I963d413dc83ef6684f58aab58a054f8541faeb85

aom_dsp/x86/intrapred_sse2.asm

diff --git a/aom_dsp/x86/intrapred_sse2.asm b/aom_dsp/x86/intrapred_sse2.asm
index c6d7fa1..9c07c5a 100644
--- a/aom_dsp/x86/intrapred_sse2.asm
+++ b/aom_dsp/x86/intrapred_sse2.asm
@@ -759,7 +759,7 @@
   psubw                 m0, m2        ; t1-tl t2-tl ... t8-tl [word]
   movq                  m2, [leftq]
   punpcklbw             m2, m1        ; l1 l2 l3 l4 l5 l6 l7 l8 [word]
-.loop
+.loop:
   pshuflw               m4, m2, 0x0   ; [63:0] l1 l1 l1 l1 [word]
   pshuflw               m3, m2, 0x55  ; [63:0] l2 l2 l2 l2 [word]
   punpcklqdq            m4, m4        ; l1 l1 l1 l1 l1 l1 l1 l1 [word]