docs: kdoc: straighten up dump_declaration()

Get rid of the excess "return" statements in dump_declaration(), along with
a line of never-executed dead code.

Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Author: Jonathan Corbet

scripts/lib/kdoc/kdoc_parser.py

@@ -878,18 +878,13 @@ def dump_declaration(self, ln, prototype):
 
         if self.entry.decl_type == "enum":
             self.dump_enum(ln, prototype)
-            return
-
-        if self.entry.decl_type == "typedef":
+        elif self.entry.decl_type == "typedef":
             self.dump_typedef(ln, prototype)
-            return
-
-        if self.entry.decl_type in ["union", "struct"]:
+        elif self.entry.decl_type in ["union", "struct"]:
             self.dump_struct(ln, prototype)
-            return
-
-        self.output_declaration(self.entry.decl_type, prototype,
-                                entry=self.entry)
+        else:
+            # This would be a bug
+            self.emit_message(ln, f'Unknown declaration type: {self.entry.decl_type}')
 
     def dump_function(self, ln, prototype):
         """