remoteproc: fix off-by-one bug in __rproc_free_vrings

Fix a nasty off-by-one bug in __rproc_free_vrings which
resulted in a memory leak and (for some platforms) failures
to reload the remote processor.

Signed-off-by: Subramaniam Chanderashekarapuram <subramaniam.ca@ti.com>
[ohad@wizery.com: reword commit log, stick with the for loop]
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

drivers/remoteproc/remoteproc_core.c

@@ -354,7 +354,7 @@ static void __rproc_free_vrings(struct rproc_vdev *rvdev, int i)
 {
 	struct rproc *rproc = rvdev->rproc;
 
-	for (i--; i > 0; i--) {
+	for (i--; i >= 0; i--) {
 		struct rproc_vring *rvring = &rvdev->vring[i];
 		int size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));