kunit: string-stream: Add kunit_alloc_string_stream()

Add function kunit_alloc_string_stream() to do a resource-managed
allocation of a string stream, and corresponding
kunit_free_string_stream() to free the resource-managed stream.

This is preparing for decoupling the string_stream
implementation from struct kunit, to reduce the amount of code
churn when that happens. Currently:
 - kunit_alloc_string_stream() only calls alloc_string_stream().
 - kunit_free_string_stream() takes a struct kunit* which
   isn't used yet.

Callers of the old alloc_string_stream() and
string_stream_destroy() are all requesting a managed allocation
so have been changed to use the new functions.

alloc_string_stream() has been temporarily made static because
its current behavior has been replaced with
kunit_alloc_string_stream().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/kunit/string-stream.c

@@ -153,7 +153,7 @@ bool string_stream_is_empty(struct string_stream *stream)
 	return list_empty(&stream->fragments);
 }
 
-struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
+static struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
 {
 	struct string_stream *stream;
 
@@ -173,3 +173,13 @@ void string_stream_destroy(struct string_stream *stream)
 {
 	string_stream_clear(stream);
 }
+
+struct string_stream *kunit_alloc_string_stream(struct kunit *test, gfp_t gfp)
+{
+	return alloc_string_stream(test, gfp);
+}
+
+void kunit_free_string_stream(struct kunit *test, struct string_stream *stream)
+{
+	string_stream_destroy(stream);
+}