boot: Make standard boot a menu

Collect these options into a menu for easier viewing.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

boot/Kconfig

@@ -372,8 +372,8 @@ config BOOT_DEFAULTS
 	  of U-Boot to boot various images. Currently much functionality is
 	  tied to enabling the command that exercises it.
 
-config BOOTSTD
-	bool "Standard boot support"
+menuconfig BOOTSTD
+	bool "Standard boot"
 	default y
 	depends on DM && OF_CONTROL && BLK
 	help
@@ -393,6 +393,8 @@ config BOOTSTD
 	        U-Boot)
 	    - bootflow - a description of how to boot (owned by the distro)
 
+if BOOTSTD
+
 config SPL_BOOTSTD
 	bool "Standard boot support in SPL"
 	depends on SPL && SPL_DM && SPL_OF_CONTROL && SPL_BLK
@@ -413,8 +415,6 @@ config VPL_BOOTSTD
 	  boot. It is enabled by default since the main purpose of VPL is to
 	  handle the firmware part of VBE.
 
-if BOOTSTD
-
 config BOOTSTD_FULL
 	bool "Enhanced features for standard boot"
 	default y if SANDBOX
@@ -673,7 +673,7 @@ config BOOTMETH_SCRIPT
 	  This provides a way to try out standard boot on an existing boot flow.
 	  It is not enabled by default to save space.
 
-endif
+endif # BOOTSTD
 
 config LEGACY_IMAGE_FORMAT
 	bool "Enable support for the legacy image format"