rtc: fix build warnings in defconfigs

RTC_CLASS is changed to bool, so 'm' is invalid.

Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/avr32/configs/atngw100_mrmt_defconfig b/arch/avr32/configs/atngw100_mrmt_defconfig
index 6cb786c..77ca4f9 100644
--- a/arch/avr32/configs/atngw100_mrmt_defconfig
+++ b/arch/avr32/configs/atngw100_mrmt_defconfig
@@ -110,7 +110,7 @@
 CONFIG_LEDS_TRIGGERS=y
 CONFIG_LEDS_TRIGGER_TIMER=y
 CONFIG_LEDS_TRIGGER_HEARTBEAT=y
-CONFIG_RTC_CLASS=m
+CONFIG_RTC_CLASS=y
 CONFIG_RTC_DRV_S35390A=m
 CONFIG_RTC_DRV_AT32AP700X=m
 CONFIG_DMADEVICES=y