mtd: introduce mtd_read 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/ubi/io.c b/drivers/mtd/ubi/io.c
index b6c8959..4333829 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -170,7 +170,7 @@
 
 	addr = (loff_t)pnum * ubi->peb_size + offset;
 retry:
-	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
 	if (err) {
 		const char *errstr = mtd_is_eccerr(err) ? " (ECC error)" : "";
 
@@ -1357,7 +1357,7 @@
 		return 0;
 	}
 
-	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf1);
+	err = mtd_read(ubi->mtd, addr, len, &read, buf1);
 	if (err && !mtd_is_bitflip(err))
 		goto out_free;
 
@@ -1421,7 +1421,7 @@
 		return 0;
 	}
 
-	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
 	if (err && !mtd_is_bitflip(err)) {
 		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
 			"read %zd bytes", err, len, pnum, offset, read);