ARM: dts: Add the core module clocks to Integrator/AP

This adds the clocks on the core module to the Integrator/AP
board: a 24MHz chrystal, and two special-purpose ICST525
dividers, one used to clock the CPU core and another auxilary
oscillator.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>