serial: 8250: move mmp|pxa uart earlycon code

There are two other drivers that bind to "mrvl,mmp-uart": the 8250_of
and the 8250_pxa. The previous one is generic and the latter is binded
to ARCH_PXA || ARCH_MMP. Now we may have pxa programming compatible
HW to support, making use of the generic 8250_of seems a good idea.
However, there's no earlycon support if we go with this solution. So
move the mmp|pxa-uart earlycon code to core 8250_early.c.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20240711160720.3488-2-jszhang@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_early.c

@@ -171,6 +171,16 @@ OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
 OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
 OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
 
+static int __init early_serial8250_rs2_setup(struct earlycon_device *device,
+					     const char *options)
+{
+	device->port.regshift = 2;
+
+	return early_serial8250_setup(device, options);
+}
+OF_EARLYCON_DECLARE(uart, "mrvl,mmp-uart", early_serial8250_rs2_setup);
+OF_EARLYCON_DECLARE(uart, "mrvl,pxa-uart", early_serial8250_rs2_setup);
+
 #ifdef CONFIG_SERIAL_8250_OMAP
 
 static int __init early_omap8250_setup(struct earlycon_device *device,

drivers/tty/serial/8250/8250_pxa.c

@@ -165,22 +165,6 @@ static struct platform_driver serial_pxa_driver = {
 
 module_platform_driver(serial_pxa_driver);
 
-#ifdef CONFIG_SERIAL_8250_CONSOLE
-static int __init early_serial_pxa_setup(struct earlycon_device *device,
-				  const char *options)
-{
-	struct uart_port *port = &device->port;
-
-	if (!(device->port.membase || device->port.iobase))
-		return -ENODEV;
-
-	port->regshift = 2;
-	return early_serial8250_setup(device, NULL);
-}
-OF_EARLYCON_DECLARE(early_pxa, "mrvl,pxa-uart", early_serial_pxa_setup);
-OF_EARLYCON_DECLARE(mmp, "mrvl,mmp-uart", early_serial_pxa_setup);
-#endif
-
 MODULE_AUTHOR("Sergei Ianovich");
 MODULE_DESCRIPTION("driver for PXA on-board UARTS");
 MODULE_LICENSE("GPL");