If you want to just stretch them to 16:9 (1920x1080), then you want to create an action that does that. Image>Image size... unlink the width and height and input 1902 pixels by 1080 pixels as the target size.
If you want to 1440x1080 plus have black bars on the sides, you want to increase the canvas size instead of the image size to 1920 by 1080 with you action.
Then batch your originals through that.
(Note: make sure you're not saving over your originals by selecting a different folder to save the results in, rather than using the "save" command.)