Take into account sub modules

tests/ui/single_component_path_imports.fixed

@@ -19,3 +19,9 @@ fn main() {
     // False positive #5154, shouldn't trigger lint.
     m!();
 }
+
+mod hello_mod {
+    
+    #[allow(dead_code)]
+    fn hello_mod() {}
+}

tests/ui/single_component_path_imports.rs

@@ -19,3 +19,9 @@ fn main() {
     // False positive #5154, shouldn't trigger lint.
     m!();
 }
+
+mod hello_mod {
+    use regex;
+    #[allow(dead_code)]
+    fn hello_mod() {}
+}

tests/ui/single_component_path_imports.stderr

@@ -6,5 +6,11 @@ LL | use regex;
    |
    = note: `-D clippy::single-component-path-imports` implied by `-D warnings`
 
-error: aborting due to previous error
+error: this import is redundant
+  --> $DIR/single_component_path_imports.rs:24:5
+   |
+LL |     use regex;
+   |     ^^^^^^^^^^ help: remove it entirely
+
+error: aborting due to 2 previous errors