In this mode, uart debug is initialized depends on
configuration from pre-loader or CONFIG_UART_DEBUG_.
The serial is not care about dts "stdout-path" and
not register into console framework any more. It's
nice to use pre-loader serial and make serial easy
to configure.
Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Change-Id: If4c68229d76b6f1710a35e3ef9a2a91cb306fa9c