add simplest test

tests/nrf51422/src/bin/test.rs

@@ -0,0 +1,15 @@
+#![no_std]
+#![no_main]
+teleprobe_meta::target!(b"nrf51-dk");
+
+use defmt::{assert, info};
+use embassy_executor::Spawner;
+use embassy_time::{Instant, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let _p = embassy_nrf::init(Default::default());
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}