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>

drivers/mtd/tests/mtd_readtest.c

@@ -148,8 +148,7 @@ static int scan_for_bad_eraseblocks(void)
 		return -ENOMEM;
 	}
 
-	/* NOR flash does not implement block_isbad */
-	if (mtd->block_isbad == NULL)
+	if (!mtd_can_have_bb(mtd))
 		return 0;
 
 	printk(PRINT_PREF "scanning for bad eraseblocks\n");

drivers/mtd/tests/mtd_speedtest.c

@@ -336,8 +336,7 @@ static int scan_for_bad_eraseblocks(void)
 		return -ENOMEM;
 	}
 
-	/* NOR flash does not implement block_isbad */
-	if (mtd->block_isbad == NULL)
+	if (!mtd_can_have_bb(mtd))
 		goto out;
 
 	printk(PRINT_PREF "scanning for bad eraseblocks\n");

drivers/mtd/tests/mtd_stresstest.c

@@ -227,8 +227,7 @@ static int scan_for_bad_eraseblocks(void)
 		return -ENOMEM;
 	}
 
-	/* NOR flash does not implement block_isbad */
-	if (mtd->block_isbad == NULL)
+	if (!mtd_can_have_bb(mtd))
 		return 0;
 
 	printk(PRINT_PREF "scanning for bad eraseblocks\n");

drivers/mtd/tests/mtd_torturetest.c

@@ -290,7 +290,7 @@ static int __init tort_init(void)
 	 * Check if there is a bad eraseblock among those we are going to test.
 	 */
 	memset(&bad_ebs[0], 0, sizeof(int) * ebcnt);
-	if (mtd->block_isbad) {
+	if (mtd_can_have_bb(mtd)) {
 		for (i = eb; i < eb + ebcnt; i++) {
 			err = mtd_block_isbad(mtd, (loff_t)i * mtd->erasesize);