driver: misc: add MXC_OCOTP Kconfig entry

Add MXC_OCOTP Kconfig entry.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>