BUG_ON() Conversion in mm/swap_state.c

this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: NEric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

mm/swap_state.c

@@ -148,8 +148,7 @@ int add_to_swap(struct page * page, gfp_t gfp_mask)
 	swp_entry_t entry;
 	int err;
 
-	if (!PageLocked(page))
-		BUG();
+	BUG_ON(!PageLocked(page));
 
 	for (;;) {
 		entry = get_swap_page();