Remove repeated vpx_integer.h from vp9_prob.h

The file vpx_integer.h has been included and used in the parent
file vp9_common.h.

Change-Id: I9c65f08353576f9ef1e5ea17244fc5ca964ec002

vp9/common/vp9_prob.h

@@ -14,7 +14,6 @@
 #include "./vpx_config.h"
 
 #include "vpx_ports/mem.h"
-#include "vpx/vpx_integer.h"
 
 #include "vp9/common/vp9_common.h"