rust: macros: remove module!'s deprecated author key

Commit 38559da6af ("rust: module: introduce `authors` key") introduced
a new `authors` key to support multiple module authors, while keeping
the old `author` key for backward compatibility.

Now that most in-tree modules have migrated to `authors`, remove:
1. The deprecated `author` key support from the module macro
2. Legacy `author` entries from remaining modules

Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250609122200.179307-1-trintaeoitogc@gmail.com
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/macros/module.rs

@@ -94,7 +94,6 @@ struct ModuleInfo {
     type_: String,
     license: String,
     name: String,
-    author: Option<String>,
     authors: Option<Vec<String>>,
     description: Option<String>,
     alias: Option<Vec<String>>,
@@ -108,7 +107,6 @@ impl ModuleInfo {
         const EXPECTED_KEYS: &[&str] = &[
             "type",
             "name",
-            "author",
             "authors",
             "description",
             "license",
@@ -134,7 +132,6 @@ impl ModuleInfo {
             match key.as_str() {
                 "type" => info.type_ = expect_ident(it),
                 "name" => info.name = expect_string_ascii(it),
-                "author" => info.author = Some(expect_string(it)),
                 "authors" => info.authors = Some(expect_string_array(it)),
                 "description" => info.description = Some(expect_string(it)),
                 "license" => info.license = expect_string_ascii(it),
@@ -179,9 +176,6 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
     // Rust does not allow hyphens in identifiers, use underscore instead.
     let ident = info.name.replace('-', "_");
     let mut modinfo = ModInfoBuilder::new(ident.as_ref());
-    if let Some(author) = info.author {
-        modinfo.emit("author", &author);
-    }
     if let Some(authors) = info.authors {
         for author in authors {
             modinfo.emit("author", &author);