Changed boot_cd_*() stubs to use echo_warning() instead of echo_status()

lib/boot/boot.in

@@ -48,9 +48,9 @@ fi
 
 # stub boot_cd_*() functions
 #
-boot_cd_pre() { echo_status "No specific boot_cd_pre() available."; }
-boot_cd_add() { echo_status "No specific boot_cd_add() available."; }
-boot_cd_post() { echo_status "No specific boot_cd_post() available."; }
+boot_cd_pre() { echo_warning "No specific boot_cd_pre() available."; }
+boot_cd_add() { echo_warning "No specific boot_cd_add() available."; }
+boot_cd_post() { echo_warning "No specific boot_cd_post() available."; }
 
 . "package/$bootloader/boot/boot.in"