mediatek: mt8183: Support coreboot configuration

mediatek: mt8183: Support coreboot configuration

When built for coreboot, we want to enable coreboot library to have
better integration. For example, serial console should be initialized by
coreboot_serial instead of hard-coded values.

Most coreboot configuration will enable memory console, which needs
larger XLAT_TABLES so MAX_XLAT_TABLES is increased; and to support that,
TZRAM_SIZE also need to be enlarged.

Change-Id: I08cf22df2fa26e48284e323d22ad8ce73a6ea803
Signed-off-by: Hung-Te Lin <hungte@chromium.org>