Remove redundant header files in vp9_loopfilter_filers.c

This cleans out the unnecessary dependency on vp9 codec-specific
data structures.

Change-Id: Iadbe431174a0f9bf9423f39ab854fc18be554bea

vp9/common/vp9_loopfilter_filters.c

@@ -11,8 +11,6 @@
 #include "./vpx_config.h"
 #include "vpx_ports/mem.h"
 #include "vp9/common/vp9_common.h"
-#include "vp9/common/vp9_loopfilter.h"
-#include "vp9/common/vp9_onyxc_int.h"
 
 static INLINE int8_t signed_char_clamp(int t) {
   return (int8_t)clamp(t, -128, 127);