MIPS: Introduce support for Platform definitions

Move platform specific definitions to the platfrom directories.

Each platform shall do the following:
1) include an entry in arch/mips/Kbuild.platforms
2) add relevant definitions to arch/mips/<platform>/Platform

This commits changes ar7 to the new scheme as an example.

Introducing a platform speecific Platfrom file has following advantages:
1) decentralization of platfrom definitions
2) simplification af arch/mips/Makefile
3) force all platfrom to build with -Werror (done in arch/mips/Kbuild)

[Ralf: Remove forgotten -Werror from AR7 Makefile]

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
To: linux-mips <linux-mips@linux-mips.org>
To: Wu Zhangjin <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1302/
Patchwork: http://patchwork.linux-mips.org/patch/1308/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index d39be47..b4ec8e9 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -209,13 +209,7 @@
 #
 # Board-dependent options and extra files
 #
-
-#
-# Texas Instruments AR7
-#
-core-$(CONFIG_AR7)		+= arch/mips/ar7/
-cflags-$(CONFIG_AR7)		+= -I$(srctree)/arch/mips/include/asm/mach-ar7
-load-$(CONFIG_AR7)		+= 0xffffffff94100000
+include $(srctree)/arch/mips/Kbuild.platforms
 
 #
 # Acer PICA 61, Mips Magnum 4000 and Olivetti M700.