mtd: nand: fix MTD_MODE_RAW writes

RAW writes were broken by 782ce79a45b3b850b108896fcf7da26754061c8f
which introduced a check of ops->ooboffs in nand_do_write_ops().

When writing in RAW mode this is called with an ops struct on the stack
of mtdchar.c:mtd_write() which does not initialise ops->ooboffs, so it
is garbage and fails this test.

This test does not make sense if ops->oobbuf is NULL, which it is in the
RAW write path, so include that in the test.

Signed-off-by: Jon Povey <jon.povey@racelogic.co.uk>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 53f4e41..1f75a1b 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2214,7 +2214,7 @@
 		memset(chip->oob_poi, 0xff, mtd->oobsize);
 
 	/* Don't allow multipage oob writes with offset */
-	if (ops->ooboffs && (ops->ooboffs + ops->ooblen > oobmaxlen))
+	if (oob && ops->ooboffs && (ops->ooboffs + ops->ooblen > oobmaxlen))
 		return -EINVAL;
 
 	while (1) {