drm/nouveau/nouveau_bo: fix potential memory leak in nouveau_bo_alloc()

nouveau_bo_alloc() allocates a memory chunk for "nvbo" with kzalloc().
When some error occurs, "nvbo" should be released. But when
WARN_ON(pi < 0)) equals true, the function return ERR_PTR without
releasing the "nvbo", which will lead to a memory leak.

We should release the "nvbo" with kfree() if WARN_ON(pi < 0)) equals true.
Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220705094306.2244103-1-niejianglei2021@163.com

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -281,8 +281,10 @@ nouveau_bo_alloc(struct nouveau_cli *cli, u64 *size, int *align, u32 domain,
 			break;
 	}
 
-	if (WARN_ON(pi < 0))
+	if (WARN_ON(pi < 0)) {
+		kfree(nvbo);
 		return ERR_PTR(-EINVAL);
+	}
 
 	/* Disable compression if suitable settings couldn't be found. */
 	if (nvbo->comp && !vmm->page[pi].comp) {