serial: sprd: add console_initcall in sprd's uart driver

Use console_initcall to save the console index we selected on the
command line to sprd_console before probe finished. Thus we can
make different processes to the uart devices during initialization
according to whether it is used for console.
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Tested-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/20190826072929.7696-3-zhang.lyra@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sprd_serial.c

@@ -1016,6 +1016,13 @@ static struct console sprd_console = {
 	.data = &sprd_uart_driver,
 };
 
+static int __init sprd_serial_console_init(void)
+{
+	register_console(&sprd_console);
+	return 0;
+}
+console_initcall(sprd_serial_console_init);
+
 #define SPRD_CONSOLE	(&sprd_console)
 
 /* Support for earlycon */