Convert various DT_CCM_* macros to use DT_CHOSEN(zephyr_ccm) and
associated macros from devicetree.h.
We remove CCM references from cortex_a and cortex_r linker scripts as
its only a feature on Cortex-M STM32 SoCs.
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>