api: move API related config options into submenu

Kconfig settings that are related to the API for standalone applications
should be in the API sub-menu and not on the top level.

CONFIG_STANDALONE_LOAD_ADDR is only relevant if standalone example
applications are built.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/api/Kconfig b/api/Kconfig
index d936272..6072288 100644
--- a/api/Kconfig
+++ b/api/Kconfig
@@ -10,9 +10,16 @@
 	depends on API
 	default 1
 
-endmenu
+config EXAMPLES
+	bool "Compile API examples"
+	depends on !SANDBOX
+	default y if ARCH_QEMU
+	help
+	  U-Boot provides an API for standalone applications. Examples are
+	  provided in directory examples/.
 
 config STANDALONE_LOAD_ADDR
+	depends on EXAMPLES
 	hex "Address in memory to link standalone applications to"
 	default 0xffffffff80200000 if MIPS && 64BIT
 	default 0x8c000000 if SH
@@ -30,3 +37,5 @@
 	  This option defines a board specific value for the address where
 	  standalone program gets loaded, thus overwriting the architecture
 	  dependent default settings.
+
+endmenu