ARM: at91: remove empty at91_init_serial function

The real function is long gone and the empty one will generate warnings
when configured without Atmel serial:
  arch/arm/mach-at91/at91rm9200_devices.c:1176: warning: 'struct at91_uart_config' declared inside parameter list
  arch/arm/mach-at91/at91rm9200_devices.c:1176: warning: its scope is only this definition or declaration, which is probably not what you want
Signed-off-by: NJoachim Eastwood <joachim.eastwood@jotron.com>
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/at91rm9200_devices.c

@@ -1173,7 +1173,6 @@ void __init at91_add_device_serial(void)
 		printk(KERN_INFO "AT91: No default serial console defined.\n");
 }
 #else
-void __init __deprecated at91_init_serial(struct at91_uart_config *config) {}
 void __init at91_register_uart(unsigned id, unsigned portnr, unsigned pins) {}
 void __init at91_set_serial_console(unsigned portnr) {}
 void __init at91_add_device_serial(void) {}