Getting rid of the od_dering_in type

We no longer need the deringing code to be generic wrt the input depth.

No change in output.

Change-Id: I2db2beb82f1816e611cd2c0438dff217d363de33
diff --git a/av1/encoder/pickdering.c b/av1/encoder/pickdering.c
index 7399086..558baee 100644
--- a/av1/encoder/pickdering.c
+++ b/av1/encoder/pickdering.c
@@ -41,7 +41,7 @@
   int r, c;
   int sbr, sbc;
   int nhsb, nvsb;
-  od_dering_in *src;
+  int16_t *src;
   int16_t *ref_coeff;
   dering_list dlist[MAX_MIB_SIZE*MAX_MIB_SIZE];
   int dir[OD_DERING_NBLOCKS][OD_DERING_NBLOCKS] = { { 0 } };