nvmem: Add driver for the i.MX IIM

This adds a readonly nvmem driver for the i.MX IC Identification Module
(IIM). The IIM is found on the older i.MX SoCs like the i.MX25, i.MX27,
i.MX31, i.MX35, i.MX51 and the i.MX53.

The IIM can control up to 8 fuse banks with 256 bit each. Not all of the
banks are equipped on the different SoCs. The actual number of fuses
differ from 512 on the i.MX27 and 1152 on the i.MX53.

The fuses are one time writable, but writing is currently not supported
in the driver.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>