i2c: New Philips PNX bus driver

New I2C bus driver for Philips ARM boards (Philips IP3204 I2C IP
block). This I2C controller can be found on (at least) PNX010x,
PNX52xx and PNX4008 Philips boards.

Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>