i2c: driver for the Synopsys DesignWare I2C controller

The i2c Linux driver for the DesignWare i2c block of Synopsys, which is meant
for AMBA Peripheral Bus. This i2c block is used on SoC chips like the ARM9
based PVG610.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>