Convert CONFIG_HUSH_INIT_VAR to Kconfig

This converts the following to Kconfig:
   CONFIG_HUSH_INIT_VAR

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/keymile/Kconfig b/board/keymile/Kconfig
index 863c07d..f22faee 100644
--- a/board/keymile/Kconfig
+++ b/board/keymile/Kconfig
@@ -11,6 +11,9 @@
 
 menu "KM Board Setup"
 
+config HUSH_INIT_VAR
+	def_bool y
+
 config KM_PNVRAM
 	hex "Pseudo RAM"
 	default 0x80000