Consolidate data structure for CDEF

Combine the primary and secondary damping factors as only one damping
factor is used according to the spec.

Change-Id: Idae886954e936c753676f41e71f7ce68e2e17eda
diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index 71c8384..abe3e61 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -1998,8 +1998,7 @@
   CdefInfo *const cdef_info = &cm->cdef_info;
 
   if (cm->allow_intrabc) return;
-  cdef_info->cdef_pri_damping = aom_rb_read_literal(rb, 2) + 3;
-  cdef_info->cdef_sec_damping = cdef_info->cdef_pri_damping;
+  cdef_info->cdef_damping = aom_rb_read_literal(rb, 2) + 3;
   cdef_info->cdef_bits = aom_rb_read_literal(rb, 2);
   cdef_info->nb_cdef_strengths = 1 << cdef_info->cdef_bits;
   for (int i = 0; i < cdef_info->nb_cdef_strengths; i++) {