fix simple example

examples/simple/src/main.rs

@@ -3,7 +3,6 @@
 #![no_std]
 
 use cortex_m_rt::entry;
-use panic_probe as _;
 use va108xx_hal as _;
 
 #[entry]
@@ -12,3 +11,10 @@ fn main() -> ! {
         cortex_m::asm::nop();
     }
 }
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    loop {
+        cortex_m::asm::nop();
+    }
+}