vp9_filter: restore vp9_bilinear_filters alignment

the declaration containing the alignment in vp9_filter.h was removed in:
eb88b17 Make vp9 subpixel match vp8

fixes a crash in 32-bit builds

Change-Id: I9a97e6b4e8e94698e43ff79d0d8bb85043b73c61

vp9/common/vp9_filter.c

@@ -12,7 +12,8 @@
 
 #include "vp9/common/vp9_filter.h"
 
-const InterpKernel vp9_bilinear_filters[SUBPEL_SHIFTS] = {
+DECLARE_ALIGNED(256, const InterpKernel,
+                vp9_bilinear_filters[SUBPEL_SHIFTS]) = {
   { 0, 0, 0, 128,   0, 0, 0, 0 },
   { 0, 0, 0, 120,   8, 0, 0, 0 },
   { 0, 0, 0, 112,  16, 0, 0, 0 },