nvmem: NXP LPC18xx EEPROM memory NVMEM driver

This commit adds support for NXP LPC18xx EEPROM memory found in NXP
LPC185x/3x and LPC435x/3x/2x/1x devices.

EEPROM size is 16384 bytes and it can be entirely read and
written/erased with 1 word (4 bytes) granularity. The last page
(128 bytes) contains the EEPROM initialization data and is not writable.

Erase/program time is less than 3ms. The EEPROM device requires a
~1500 kHz clock (min 800 kHz, max 1600 kHz) that is generated dividing
the system bus clock by the division factor, contained in the divider
register (minus 1 encoded).

EEPROM will be kept in Power Down mode except during read/write calls.

Signed-off-by: Ariel D'Alessandro <ariel@vanguardiasur.com.ar>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>