ARM: at91/rtc-at91sam9: each SoC can select the RTT device to use

For the RTT as RTC driver rtc-at91sam9, the platform_device structure
is filled during SoC initialization. This will allow to convert this
RTC driver as a standard platform driver.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/at91sam9g45_devices.c b/arch/arm/mach-at91/at91sam9g45_devices.c
index 8c036ff..81d1adf 100644
--- a/arch/arm/mach-at91/at91sam9g45_devices.c
+++ b/arch/arm/mach-at91/at91sam9g45_devices.c
@@ -1204,8 +1204,18 @@
 	.num_resources	= ARRAY_SIZE(rtt_resources),
 };
 
+#if IS_ENABLED(CONFIG_RTC_DRV_AT91SAM9)
+static void __init at91_add_device_rtt_rtc(void)
+{
+	at91sam9g45_rtt_device.name = "rtc-at91sam9";
+}
+#else
+static void __init at91_add_device_rtt_rtc(void) {}
+#endif
+
 static void __init at91_add_device_rtt(void)
 {
+	at91_add_device_rtt_rtc();
 	platform_device_register(&at91sam9g45_rtt_device);
 }