[MTD] [NAND] sh_flctl: add support for Renesas SuperH FLCTL

Several Renesas SuperH CPU has FLCTL. The FLCTL support NAND Flash.
This driver support SH7723.

Signed-off-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>