Fix kernel driver probe not freeing endpoint

If an error occurs after the kernel driver probe has created a rpmsg
endpoint, the endpoint is not freed during the clean up.

Clean up code for the endpoint has now been added to resolve this.

Change-Id: I9259713f2b7dcf4926e6f317c57f2791ab3463de
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
diff --git a/kernel/ethosu_device.c b/kernel/ethosu_device.c
index 6987215..1a2e7f7 100644
--- a/kernel/ethosu_device.c
+++ b/kernel/ethosu_device.c
@@ -459,7 +459,7 @@
 
 	ret = ethosu_mailbox_init(&edev->mailbox, dev, edev->ept);
 	if (ret)
-		goto device_unregister;
+		goto free_rpmsg_ept;
 
 	ethosu_mailbox_ping(&edev->mailbox);
 
@@ -506,6 +506,9 @@
 deinit_mailbox:
 	ethosu_mailbox_deinit(&edev->mailbox);
 
+free_rpmsg_ept:
+	rpmsg_destroy_ept(edev->ept);
+
 device_unregister:
 	device_unregister(dev);