The timing calculations used by the PXA platforms did not always take
account of the timings handed to us by PCMCIA, and where it did, it
assumed IO timings for memory windows.

We fix this, and provide a generic function which calculates the
required timings (in nanoseconds) for IO, memory and attribute
windows.  The SOC drivers only have to convert this information to
whatever format the hardware requires to achieve at least these
timing parameters.