mtd: nand: Sync with Linux v4.6

Updates the NAND code to match Linux v4.6.  The previous sync was from
Linux v4.1 in commit d3963721d93fafa.

Note that none of the individual NAND drivers tracked Linux closely
enough to be synced themselves, other than manually applying a few
cross-tree changes.

Signed-off-by: Scott Wood <oss@buserror.net>
Tested-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/mtd/nand/ndfc.c b/drivers/mtd/nand/ndfc.c
index ee353c7..0a9849e 100644
--- a/drivers/mtd/nand/ndfc.c
+++ b/drivers/mtd/nand/ndfc.c
@@ -1,6 +1,6 @@
 /*
  * Overview:
- *   Platform independend driver for NDFC (NanD Flash Controller)
+ *   Platform independent driver for NDFC (NanD Flash Controller)
  *   integrated into IBM/AMCC PPC4xx cores
  *
  * (C) Copyright 2006-2009