UBI: introduce helpers dbg_chk_{io, gen}

With this patch code is a bit more readable and there's no
generated code or functionality impact.
Furthermore, this abstracts implementation details and
will allow to change ubi_debug_info in a less invasive way.

Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
index 72fed30..c071d41 100644
--- a/drivers/mtd/ubi/attach.c
+++ b/drivers/mtd/ubi/attach.c
@@ -1448,7 +1448,7 @@
 		goto out_wl;
 
 #ifdef CONFIG_MTD_UBI_FASTMAP
-	if (ubi->fm && ubi->dbg->chk_gen) {
+	if (ubi->fm && ubi_dbg_chk_gen(ubi)) {
 		struct ubi_attach_info *scan_ai;
 
 		scan_ai = alloc_ai("ubi_ckh_aeb_slab_cache");
@@ -1498,7 +1498,7 @@
 	struct ubi_ainf_peb *aeb, *last_aeb;
 	uint8_t *buf;
 
-	if (!ubi->dbg->chk_gen)
+	if (!ubi_dbg_chk_gen(ubi))
 		return 0;
 
 	/*