firmware: raspberrypi: fix possible memory leak in rpi_firmware_probe()

In rpi_firmware_probe(), if mbox_request_channel() fails, the 'fw' will
not be freed through rpi_firmware_delete(), fix this leak by calling
kfree() in the error path.

Fixes: 1e7c573 ("firmware: raspberrypi: Keep count of all consumers")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221117070636.3849773-1-yangyingliang@huawei.com
Acked-by: Joel Savitz <jsavitz@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/raspberrypi.c

@@ -272,6 +272,7 @@ static int rpi_firmware_probe(struct platform_device *pdev)
 		int ret = PTR_ERR(fw->chan);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
+		kfree(fw);
 		return ret;
 	}