i2c: lpc2k: add driver

Add support for the I2C controller found on several NXP devices
including LPC2xxx, LPC178x/7x and LPC18xx/43xx. The controller
is implemented as a state machine and the driver act upon the
state changes when the bus is accessed.

The I2C controller supports master/slave operation, bus
arbitration, programmable clock rate, and speeds up to 1 Mbit/s.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>