MXC: mxc_nand: set NFC registers after reset

This patch allows the mxc_nand driver to reset the NAND
flash controller.  NFC registers are (re-)set after
completion of the reset, as a reset will have reverted
the NFC registers to their default values.

Signed-off-by: Ivo Clarysse <ivo.clarysse@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>