rk27xx lcd code rework

Use DMA engine for fullscreen updates and bypass mode for partial
updates. This gives major boost on rk27generic:
default ARM:AHB:APB 200💯50
HEAD    1/1:  26.3fps 1/4: 105.0fps
patched 1/1: 116.5fps 1/4: 249.5fps

with freq scalling NORMAL mode ARM:AHB:APB 50:50:50
HEAD    1/1:  13.1fps 1/4: 52.5fps
patched 1/1:  54.5fps 1/4: 119.0fps

Tested on rk27generic noname DAP and on Hifimans.

Change-Id: Id9dd4d2d61542c7ea6b5c6336b170d6357cefde9

firmware/target/arm/rk27xx/hm801/lcd-target.h

@@ -0,0 +1,27 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C)  2012 Andrew Ryabinin
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#ifndef LCD_TARGET_H
+#define LCD_TARGET_H
+
+#define LCD_DATABUS_WIDTH LCDIF_16BIT
+
+#endif