mtd: introduce mtd_can_have_bb helper

This patch introduces new 'mtd_can_have_bb()' helper function which checks
whether the flash can have bad eraseblocks. Then it changes all the
direct 'mtd->block_isbad' use cases with 'mtd_can_have_bb()'.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index c8540b8..a4c8f67 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -169,7 +169,7 @@
 			cxt->nextpage = 0;
 	}
 
-	while (mtd->block_isbad) {
+	while (mtd_can_have_bb(mtd)) {
 		ret = mtd_block_isbad(mtd, cxt->nextpage * record_size);
 		if (!ret)
 			break;
@@ -257,7 +257,7 @@
 	size_t retlen;
 
 	for (page = 0; page < cxt->oops_pages; page++) {
-		if (mtd->block_isbad &&
+		if (mtd_can_have_bb(mtd) &&
 		    mtd_block_isbad(mtd, page * record_size))
 			continue;
 		/* Assume the page is used */