Remove PALETTE flag

This experiment is now adopted as it was cleared by Tapas.

Note: Palette use can still be controlled by command-line option
"--tune-content=..." in 'aomenc'.

Change-Id: I832f49f20f60c34bdef5b424755849c496687e87
diff --git a/av1/common/pred_common.h b/av1/common/pred_common.h
index aab026e..ffdeb6b 100644
--- a/av1/common/pred_common.h
+++ b/av1/common/pred_common.h
@@ -86,14 +86,14 @@
 #endif  // CONFIG_INTRA_INTERP
 #endif  // CONFIG_EXT_INTRA
 
-#if CONFIG_PALETTE && CONFIG_PALETTE_DELTA_ENCODING
+#if CONFIG_PALETTE_DELTA_ENCODING
 // Get a list of palette base colors that are used in the above and left blocks,
 // referred to as "color cache". The return value is the number of colors in the
 // cache (<= 2 * PALETTE_MAX_SIZE). The color values are stored in "cache"
 // in ascending order.
 int av1_get_palette_cache(const MODE_INFO *above_mi, const MODE_INFO *left_mi,
                           int plane, uint16_t *cache);
-#endif  // CONFIG_PALETTE && CONFIG_PALETTE_DELTA_ENCODING
+#endif  // CONFIG_PALETTE_DELTA_ENCODING
 
 int av1_get_intra_inter_context(const MACROBLOCKD *xd);