hikey: make console configurable
hikey: make console configurable

96boards HiKey defaults to UART3 for console.
We keep the default at UART0 to keep secure world logs separate,
but gives users an option to use UART3 if preferred.
Build with:

make ... CFG_HIKEY_UART3=y

Signed-off-by: Victor Chong <4aabb03bd6dd29c44a49684d87b08ac07e10b492@linaro.org>
Reviewed-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Reviewed-by: Pascal Brand <0b55292d2562685bad4ce52d64f802e8f1cd299e@linaro.org>

Microsoft/optee_os,cedric-chaumont-st-dev/optee_os,Microsoft/optee_os,pascal-brand-st-dev/optee_os,cedric-chaumont-st-dev/optee_os,matt2048/optee_os,pascal-brand-st-dev/optee_os,cedric-chaumont-st-dev/optee_os,matt2048/optee_os,cedric-chaumont-st-dev/optee_os,pascal-brand-st-dev/optee_os,Microsoft/optee_os,Microsoft/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,matt2048/optee_os,matt2048/optee_os,Microsoft/optee_os