arm: Move FSL_HAS_DP_DDR and NUM_DDR_CONTROLLERS to Kconfig

Move this option to Kconfig and clean up existing uses.
NUM_DDR_CONTROLLERS is also used by PowerPC SoCs.

Signed-off-by: York Sun <york.sun@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2 files changed