remove unused check

that was added in #140 but it's no longer required

tests/cfail/init-extra-late-resources.rs

@@ -0,0 +1,15 @@
+#![no_main]
+#![no_std]
+
+extern crate lm3s6965;
+extern crate panic_halt;
+extern crate rtfm;
+
+use rtfm::app;
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init(_: init::Context) -> init::LateResources {}
+    //~^ error: `init` signature must be `fn(init::Context)` if there are no late resources
+};

tests/cfail/init-missing-late-resources.rs

@@ -0,0 +1,17 @@
+#![no_main]
+#![no_std]
+
+extern crate lm3s6965;
+extern crate panic_halt;
+extern crate rtfm;
+
+use rtfm::app;
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static mut X: i32 = ();
+
+    #[init]
+    fn init(_: init::Context) {}
+    //~^ error: late resources have been specified so `init` must return `init::LateResources`
+};