arch: Make board selection choices optional

By making the board selections optional, every defconfig will include
the board selection when running savedefconfig so if a new board is
added to the top of the list of choices the former top's defconfig will
still be correct.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/board/amcc/canyonlands/Kconfig b/board/amcc/canyonlands/Kconfig
index ef66ad4..a655dbc 100644
--- a/board/amcc/canyonlands/Kconfig
+++ b/board/amcc/canyonlands/Kconfig
@@ -11,6 +11,7 @@
 
 choice BOARD_TYPE
 	prompt "Select which board to build for"
+	optional
 
 config CANYONLANDS
 	bool "Glacier"
diff --git a/board/coreboot/Kconfig b/board/coreboot/Kconfig
index dc9b70f..ede6065 100644
--- a/board/coreboot/Kconfig
+++ b/board/coreboot/Kconfig
@@ -8,6 +8,7 @@
 
 choice
 	prompt "Mainboard model"
+	optional
 
 config TARGET_COREBOOT
 	bool "coreboot"
diff --git a/board/dbau1x00/Kconfig b/board/dbau1x00/Kconfig
index 1286e45..b813adb 100644
--- a/board/dbau1x00/Kconfig
+++ b/board/dbau1x00/Kconfig
@@ -13,6 +13,7 @@
 
 choice
 	prompt "Select au1x00 SoC type"
+	optional
 
 config DBAU1100
 	bool "Select AU1100"
diff --git a/board/google/Kconfig b/board/google/Kconfig
index 302f68e..e9559c9 100644
--- a/board/google/Kconfig
+++ b/board/google/Kconfig
@@ -8,6 +8,7 @@
 
 choice
 	prompt "Mainboard model"
+	optional
 
 config TARGET_CHROMEBOOK_LINK
 	bool "Chromebook link"
diff --git a/board/intel/Kconfig b/board/intel/Kconfig
index 7fe21b9..3d9ecf0 100644
--- a/board/intel/Kconfig
+++ b/board/intel/Kconfig
@@ -8,6 +8,7 @@
 
 choice
 	prompt "Mainboard model"
+	optional
 
 config TARGET_CROWNBAY
 	bool "Crown Bay"
diff --git a/board/micronas/vct/Kconfig b/board/micronas/vct/Kconfig
index 288a1ae..c518079 100644
--- a/board/micronas/vct/Kconfig
+++ b/board/micronas/vct/Kconfig
@@ -13,6 +13,7 @@
 
 choice
 	prompt "Board variant"
+	optional
 
 config VCT_PLATINUM
 	bool "Enable VCT_PLATINUM"
diff --git a/board/seco/Kconfig b/board/seco/Kconfig
index dcb1ac8..af16697 100644
--- a/board/seco/Kconfig
+++ b/board/seco/Kconfig
@@ -2,6 +2,7 @@
 
 choice
 	prompt "SECO i.MX6 Board variant"
+	optional
 
 config SECOMX6_Q7
 	bool "Q7"
@@ -16,6 +17,7 @@
 
 choice
 	prompt "SECO i.MX6 SoC variant"
+	optional
 
 config SECOMX6Q
 	bool "i.MX6Q"
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index a60d028..c60c81d 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -18,6 +18,7 @@
 
 choice
 	prompt "Sunxi SoC Variant"
+	optional
 
 config MACH_SUN4I
 	bool "sun4i (Allwinner A10)"