serial: ar933x_uart: Fix build failure with disabled console

Andrey has reported on OpenWrt's bug tracking system[1], that he
currently can't use ar93xx_uart as pure serial UART without console
(CONFIG_SERIAL_8250_CONSOLE and CONFIG_SERIAL_AR933X_CONSOLE undefined),
because compilation ends with following error:

ar933x_uart.c: In function 'ar933x_uart_console_write':
ar933x_uart.c:550:14: error: 'struct uart_port' has no
member named 'sysrq'

So this patch moves all the code related to console handling behind
series of CONFIG_SERIAL_AR933X_CONSOLE ifdefs.

1. https://bugs.openwrt.org/index.php?do=details&task_id=2152

Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Jiri Slaby <[e-mail]>
Cc: Andrey Batyiev <[e-mail]>
Reported-by: Andrey Batyiev <[e-mail]>
Tested-by: Andrey Batyiev <[e-mail]>
Signed-off-by: Petr Štetiar <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/ar933x_uart.c

···
 	struct clk		*clk;
 };
 
-static inline bool ar933x_uart_console_enabled(void)
-{
-	return IS_ENABLED(CONFIG_SERIAL_AR933X_CONSOLE);
-}
-
 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
 					    int offset)
 {
···
 	.verify_port	= ar933x_uart_verify_port,
 };
 
+#ifdef CONFIG_SERIAL_AR933X_CONSOLE
 static struct ar933x_uart_port *
 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
 
···
 	.index		= -1,
 	.data		= &ar933x_uart_driver,
 };
-
-static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
-{
-	if (!ar933x_uart_console_enabled())
-		return;
-
-	ar933x_console_ports[up->port.line] = up;
-}
+#endif /* CONFIG_SERIAL_AR933X_CONSOLE */
 
 static struct uart_driver ar933x_uart_driver = {
 	.owner		= THIS_MODULE,
···
 	baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
 	up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
 
-	ar933x_uart_add_console_port(up);
+#ifdef CONFIG_SERIAL_AR933X_CONSOLE
+	ar933x_console_ports[up->port.line] = up;
+#endif
 
 	ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
 	if (ret)
···
 {
 	int ret;
 
-	if (ar933x_uart_console_enabled())
-		ar933x_uart_driver.cons = &ar933x_uart_console;
+#ifdef CONFIG_SERIAL_AR933X_CONSOLE
+	ar933x_uart_driver.cons = &ar933x_uart_console;
+#endif
 
 	ret = uart_register_driver(&ar933x_uart_driver);
 	if (ret)