ARM: pxa: Transition pxa25x, pxa27x, pxa3xx to clk framework

Transition the PXA25x, PXA27x and PXA3xx CPUs to the clock framework.
This transition still enables legacy platforms to run without device
tree as before, ie relying on platform data encoded in board specific
files.

This is the last step of clock framework transition for pxa
platforms. It was tested on lubbock (pxa25x), mioa701 (pxa27x) and
zylonite (pxa3xx).

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>