mk: report an error when the CFG_ARM64{32}_core both missing
mk: report an error when the CFG_ARM64{32}_core both missing

When the CFG_ARM64_core and CFG_ARM32_core are both missing defined by
the platform, it will raise unexpected compile errors. In this patch,
report an compile error when neither the CFG_ARM64_core nor
CFG_ARM32_core is defined.

Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Signed-off-by: Zeng Tao <ae5c7f8f383511cb075e5cee5f277c5f19ea314f@hisilicon.com>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os