toolchain: get rid of "binary" for external toolchain

We no longer have an option for external source based toolchains,
so get rid of "binary".

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/Config.in

@@ -12,7 +12,7 @@ config BR2_TOOLCHAIN_BUILDROOT
 	bool "Buildroot toolchain"
 
 config BR2_TOOLCHAIN_EXTERNAL
-	bool "External binary toolchain"
+	bool "External toolchain"
 
 endchoice