ARM: pxa: Transition pxa25x and pxa27x to clk framework

Transition the PXA25x and PXA27x 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.

The transition breaks the previous clocks activation of pin
control (gpio11 and gpio12). Machine files should be amended to take
that into account.

This is the last step of clock framework transition for pxa25x and
pxa27x, leaving only pxa3xx for further work.

Reviewed-by: Michael Turquette <mturquette@linaro.org>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>