UBI: Add initial support for fastmap self checks

Using this debugfs knob fastmap self checks can be controlled.

Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Tanya Brokhman <tlinder@codeaurora.org>

drivers/mtd/ubi/debug.h

@@ -127,4 +127,9 @@ static inline int ubi_dbg_chk_gen(const struct ubi_device *ubi)
 {
 	return ubi->dbg.chk_gen;
 }
+
+static inline int ubi_dbg_chk_fastmap(const struct ubi_device *ubi)
+{
+	return ubi->dbg.chk_fastmap;
+}
 #endif /* !__UBI_DEBUG_H__ */