Replace DC_PRED with UV_DC_PRED for chroma

When using uv_mode the corresponding enum is the UV_PREDICTION_MODE not
the PREDICTION_MODE enum.

Change-Id: I44b19e4db5947a2d44281430b34ed61b82f999eb

av1/encoder/rdopt.c

@@ -6068,7 +6068,7 @@ static int64_t rd_pick_intra_sbuv_mode(const AV1_COMP *const cpi, MACROBLOCK *x,
     }
 #endif  // CONFIG_EXT_INTRA
 #if CONFIG_FILTER_INTRA
-    if (mbmi->sb_type >= BLOCK_8X8 && mode == DC_PRED)
+    if (mbmi->sb_type >= BLOCK_8X8 && mode == UV_DC_PRED)
       this_rate += av1_cost_bit(cpi->common.fc->filter_intra_probs[1], 0);
 #endif  // CONFIG_FILTER_INTRA
     if (try_palette && mode == UV_DC_PRED)