serial: xuartps: add __init to earlycon write method

Early console functions are only used during the early boot stage.
This change just saves a small amount of memory footprint.

Signed-off-by: Masahiro Yamada <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/xilinx_uartps.c

···
 	writel(ch, port->membase + CDNS_UART_FIFO_OFFSET);
 }
 
-static void cdns_early_write(struct console *con, const char *s, unsigned n)
+static void __init cdns_early_write(struct console *con, const char *s,
+				    unsigned n)
 {
 	struct earlycon_device *dev = con->data;