[U-Boot] Zoom hw reset

[Tom Rix]

For arm/next

This patch enables hw resetting of zoom1 and zoom2. 
This is done through the twl4030 part.  Since this part is not currently
supported, start an twl4030_i2c device.  In testing it was found that I2C
was broken on Zoom1 and Zoom2. I2C was fixed by improving the
initialization of its sampling clock.  

The reset changes were run tested on zoom1 and zoom2.

The I2C changes were run tested on zoom1, zoom2, beagle and overo.
The 400kHz case was run tested on a variant of the zoom1 configuration.