[CFL] Move store flag to CFL_CTX

With recent changes, it is now possible to store the storage
flag inside the CFL_CTX. This simplifies the implementation
and will allow reuse in the decoder.

This change does not alter the bitstream.

Change-Id: Ibb8aebdd3d06f8765d40248ece8a038892e87032
diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 4a9359d..632acb5 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -5949,7 +5949,7 @@
 
   if (!is_inter) {
 #if CONFIG_CFL
-    x->cfl_store_y = 1;
+    xd->cfl->store_y = 1;
 #endif  // CONFIG_CFL
     int plane;
     mbmi->skip = 1;
@@ -5958,7 +5958,7 @@
                                    mi_row, mi_col);
     }
 #if CONFIG_CFL
-    x->cfl_store_y = 0;
+    xd->cfl->store_y = 0;
 #endif  // CONFIG_CFL
     if (!dry_run) {
       sum_intra_stats(td->counts, xd, mi, xd->above_mi, xd->left_mi,