mtd: introduce mtd_block_isbad interface

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/ssfdc.c b/drivers/mtd/ssfdc.c
index 0e68813..ab2a52a 100644
--- a/drivers/mtd/ssfdc.c
+++ b/drivers/mtd/ssfdc.c
@@ -122,7 +122,7 @@
 	 * is not SSFDC formatted
 	 */
 	for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
-		if (!mtd->block_isbad(mtd, offset)) {
+		if (mtd_block_isbad(mtd, offset)) {
 			ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen,
 				       sect_buf);
 
@@ -255,7 +255,7 @@
 	for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
 			phys_block++) {
 		offset = (unsigned long)phys_block * ssfdc->erase_size;
-		if (mtd->block_isbad(mtd, offset))
+		if (mtd_block_isbad(mtd, offset))
 			continue;	/* skip bad blocks */
 
 		ret = read_raw_oob(mtd, offset, oob_buf);