In the commit 40492a0
(MIPS: add common header file for DEBUG_LL via NS16550)
introduced common DEBUG_LL via NS16550 for MIPS
(see file arch/mips/include/debug_ll_ns16550.h).

In the commit 1cbe2b2
(MIPS: XBurst: add Ritmix RZX-50 board support)
the file debug_ll_ns16550.h used in
the file arch/mips/mach-xburst/include/mach/debug_ll.h.

Usage looks like this:

------------------------------------------------
+#ifdef CONFIG_BOARD_RZX50
+#include <mach/debug_ll_jz4755.h>
+#endif
+
+#include <debug_ll_ns16550.h>
------------------------------------------------

So after adding another board (e.g. A320) we will have something like this:

------------------------------------------------
 #ifdef CONFIG_BOARD_RZX50
 #include <mach/debug_ll_jz4755.h>
 #endif

+#ifdef CONFIG_BOARD_A320
+#include <mach/debug_ll_jz4740.h>
+#endif

 #include <debug_ll_ns16550.h>
------------------------------------------------

This approach has disadvantage:
* the files mach/debug_ll_jz4740.h and mach/debug_ll_jz4755.h
(they go to arch/mips/arch-xburst) are __BOARD-SPECIFIC__
(not SOC- or mach-specific!); The file mach-xburst/include/mach/debug_ll.h
is outside board directory, but it contains some board related information.

This commit introduce a more suitable solution.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>