serial: dcc: Move driver to DM

Enabling this driver requires some DT changes.
Adding DCC to root or main bus:
dcc: dcc {
	compatible = "arm,dcc";
	u-boot,dm-pre-reloc;
};

Extend alias list to link DCC:
	serial0 = &uart0;
	serial1 = &uart1;
	serial2 = &dcc;

Change stdout-path to point to dcc port.
	stdout-path = "serial2:115200n8";

Also add support for debug uart to help with early debug.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index fac3176..92d4212 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -119,6 +119,17 @@
 	  You will need to provide parameters to make this work. The driver will
 	  be available until the real driver-model serial is running.
 
+config DEBUG_UART_ARM_DCC
+	bool "ARM DCC"
+	help
+	  Select this to enable a debug UART using the ARM JTAG DCC port.
+	  The DCC port can be used for very early debugging and doesn't require
+	  any additional setting like address/baudrate/clock. On systems without
+	  any serial interface this is the easiest way how to get console.
+	  Every ARM core has own DCC port which is the part of debug interface.
+	  This port is available at least on ARMv6, ARMv7, ARMv8 and XScale
+	  architectures.
+
 config DEBUG_UART_ZYNQ
 	bool "Xilinx Zynq"
 	help