mtd: nand: xway: remove manual reset

nand_scan() already resets the NAND flash chip, this driver does not
have to call it manually. The xway_reset_chip() functions does the same
as the normal NAND reset function. The waiting for the NAND_WAIT_WR_C
is done in xway_cmd_ctrl().

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>