kconfig: add CONFIG_SYS_{ARCH, CPU, ...} type def to arch/Kconfig

This commit adds the type definitions (+ help messages) of
CONFIG_SYS_{ARCH, CPU, SOC, VENDOR, BOARD, CONFIG_NAME} to arch/Kconfig,
which would save lots of type defs for taget boards.
(See also the next commit.)

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

arch/Kconfig

@@ -49,6 +49,62 @@ config X86
 
 endchoice
 
+config SYS_ARCH
+	string
+	help
+	  This option should contain the architecture name to build the
+	  appropriate arch/<CONFIG_SYS_ARCH> directory.
+	  All the architectures should specify this option correctly.
+
+config SYS_CPU
+	string
+	help
+	  This option should contain the CPU name to build the correct
+	  arch/<CONFIG_SYS_ARCH>/cpu/<CONFIG_SYS_CPU> directory.
+
+	  This is optional.  For those targets without the CPU directory,
+	  leave this option empty.
+
+config SYS_SOC
+	string
+	help
+	  This option should contain the SoC name to build the directory
+	  arch/<CONFIG_SYS_ARCH>/cpu/<CONFIG_SYS_CPU>/<CONFIG_SYS_SOC>.
+
+	  This is optional.  For those targets without the SoC directory,
+	  leave this option empty.
+
+config SYS_VENDOR
+	string
+	help
+	  This option should contain the vendor name of the target board.
+	  If it is set and
+	  board/<CONFIG_SYS_VENDOR>/common/Makefile exists, the vendor common
+	  directory is compiled.
+	  If CONFIG_SYS_BOARD is also set, the sources under
+	  board/<CONFIG_SYS_VENDOR>/<CONFIG_SYS_BOARD> directory are compiled.
+
+	  This is optional.  For those targets without the vendor directory,
+	  leave this option empty.
+
+config SYS_BOARD
+	string
+	help
+	  This option should contain the name of the target board.
+	  If it is set, either board/<CONFIG_SYS_VENDOR>/<CONFIG_SYS_BOARD>
+	  or board/<CONFIG_SYS_BOARD> directory is compiled depending on
+	  whether CONFIG_SYS_VENDOR is set or not.
+
+	  This is optional.  For those targets without the board directory,
+	  leave this option empty.
+
+config SYS_CONFIG_NAME
+	string
+	help
+	  This option should contain the base name of board header file.
+	  The header file include/configs/<CONFIG_SYS_CONFIG_NAME>.h
+	  should be included from include/config.h.
+
 source "arch/arc/Kconfig"
 source "arch/arm/Kconfig"
 source "arch/avr32/Kconfig"