kconfig: add CONFIG_SUPPORT_SPL

CONFIG_SPL should not be enabled for boards that do not have SPL.
CONFIG_SUPPORT_SPL introduced by this commit should be "select"ed
by boards with SPL support and CONFIG_SPL should depend on it.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/arm926ejs/davinci/Kconfig b/arch/arm/cpu/arm926ejs/davinci/Kconfig
index 4c18ab6..1791cef 100644
--- a/arch/arm/cpu/arm926ejs/davinci/Kconfig
+++ b/arch/arm/cpu/arm926ejs/davinci/Kconfig
@@ -8,18 +8,22 @@
 
 config TARGET_IPAM390
 	bool "IPAM390 board"
+	select SUPPORT_SPL
 
 config TARGET_DA830EVM
 	bool "DA830 EVM board"
 
 config TARGET_DA850EVM
 	bool "DA850 EVM board"
+	select SUPPORT_SPL
 
 config TARGET_CAM_ENC_4XX
 	bool "CAM ENC 4xx board"
+	select SUPPORT_SPL
 
 config TARGET_HAWKBOARD
 	bool "Hawkboard"
+	select SUPPORT_SPL
 
 config TARGET_DAVINCI_DM355EVM
 	bool "DM355 EVM board"