UBI: small debugging code optimization

The @ubi->dbg_peb_buf is needed only when paranoid checks are
enabled, not when debugging in general is enabled.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 76ec79b..749007e 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -443,7 +443,7 @@
 	void *peb_buf2;
 	struct mutex buf_mutex;
 	struct mutex ckvol_mutex;
-#ifdef CONFIG_MTD_UBI_DEBUG
+#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
 	void *dbg_peb_buf;
 	struct mutex dbg_buf_mutex;
 #endif