mtd: nand: convert ONFI mode into data interface

struct nand_data_interface is the designated type to pass to
the NAND drivers to configure the timing. To simplify further
patches convert the onfi_sdr_timings array from type struct
nand_sdr_timings nand_data_interface.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Linux commit: b1dd3ca203fccd111926c3f6ac59bf903ec62b05]
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index e321e3e..a633fd0 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -1134,6 +1134,11 @@
 }
 #endif
 
+int onfi_init_data_interface(struct nand_chip *chip,
+			     struct nand_data_interface *iface,
+			     enum nand_data_interface_type type,
+			     int timing_mode);
+
 /*
  * Check if it is a SLC nand.
  * The !nand_is_slc() can be used to check the MLC/TLC nand chips.