[U-Boot] V3 Zoom hw reset

[Tom Rix]

The i2c patch is a cleaned up version of the one I RFC-ed to the list
earlier.  It addresses Nishanth's concerns by using the kernel's algorithm
and by making the major parameters overridable by a board config. 
Jean's request for no weak function is addressed by this being done only
with #defines.  I have reverified on the hw listed in the commit. 

The twl4030 patch I don't think anyone had a problem with. 

The twl4030 hw reset has been generalized.  After analyzing beagle 
schematics, I believe this can be used by anyone with supporting hw.
So the function stays in power.c and the #ifdef's are removed.