wifi: mwifiex: fix memory leak in mwifiex_histogram_read()

Always free the zeroed page on return from 'mwifiex_histogram_read()'.

Fixes: cbf6e055 ("mwifiex: add rx histogram statistics support")
Acked-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230802160726.85545-1-dmantipov@yandex.ru

drivers/net/wireless/marvell/mwifiex/debugfs.c

@@ -253,8 +253,11 @@ mwifiex_histogram_read(struct file *file, char __user *ubuf,
 	if (!p)
 		return -ENOMEM;
 
-	if (!priv || !priv->hist_data)
-		return -EFAULT;
+	if (!priv || !priv->hist_data) {
+		ret = -EFAULT;
+		goto free_and_exit;
+	}
+
 	phist_data = priv->hist_data;
 
 	p += sprintf(p, "\n"
@@ -309,6 +312,8 @@ mwifiex_histogram_read(struct file *file, char __user *ubuf,
 	ret = simple_read_from_buffer(ubuf, count, ppos, (char *)page,
 				      (unsigned long)p - page);
 
+free_and_exit:
+	free_page(page);
 	return ret;
 }