UBI: prepare debugging stuff to further debugfs conversion

We'll need the 'struct ubi_device *ubi' pointer in every debugging function (to
access the ->dbg field), so add this pointer to all the functions implementing
UBI debugging test modes like 'ubi_dbg_is_bitflip()' etc.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index bf13ca2..42c684c 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -616,7 +616,7 @@
 	list_add_tail(&wrk->list, &ubi->works);
 	ubi_assert(ubi->works_count >= 0);
 	ubi->works_count += 1;
-	if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled())
+	if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled(ubi))
 		wake_up_process(ubi->bgt_thread);
 	spin_unlock(&ubi->wl_lock);
 }
@@ -1367,7 +1367,7 @@
 
 		spin_lock(&ubi->wl_lock);
 		if (list_empty(&ubi->works) || ubi->ro_mode ||
-		    !ubi->thread_enabled || ubi_dbg_is_bgt_disabled()) {
+		    !ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			spin_unlock(&ubi->wl_lock);
 			schedule();