vbe: Enable command only with BOOTSTD_FULL

Avoid enabling this command by default. This saves about 1KB of code
space.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 211ebe9..8ea064b 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -333,7 +333,7 @@
 config CMD_VBE
 	bool "vbe - Verified Boot for Embedded"
 	depends on BOOTMETH_VBE
-	default y
+	default y if BOOTSTD_FULL
 	help
 	  Provides various subcommands related to VBE, such as listing the
 	  available methods, looking at the state and changing which method