rust: samples: add a module parameter to the rust_minimal sample

Showcase the rust module parameter support by adding a module parameter to
the `rust_minimal` sample.

Reviewed-by: Benno Lossin <[e-mail]>
Signed-off-by: Andreas Hindborg <[e-mail]>
Tested-by: Daniel Gomez <[e-mail]>
Signed-off-by: Daniel Gomez <[e-mail]>

samples/rust/rust_minimal.rs

···
     authors: ["Rust for Linux Contributors"],
     description: "Rust minimal sample",
     license: "GPL",
+    params: {
+        test_parameter: i64 {
+            default: 1,
+            description: "This parameter has a default of 1",
+        },
+    },
 }
 
 struct RustMinimal {
···
     fn init(_module: &'static ThisModule) -> Result<Self> {
         pr_info!("Rust minimal sample (init)\n");
         pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
+        pr_info!(
+            "test_parameter: {}\n",
+            *module_parameters::test_parameter.value()
+        );
 
         let mut numbers = KVec::new();
         numbers.push(72, GFP_KERNEL)?;