ARM: sunxi: Add A31 RTC driver to multi_v7_defconfig

Now that we have a driver for A31's RTC, enable it
in multi_v7_defconfig.
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/configs/multi_v7_defconfig

@@ -349,6 +349,7 @@ CONFIG_RTC_DRV_TPS65910=y
 CONFIG_RTC_DRV_EM3027=y
 CONFIG_RTC_DRV_PL031=y
 CONFIG_RTC_DRV_VT8500=y
+CONFIG_RTC_DRV_SUN6I=y
 CONFIG_RTC_DRV_SUNXI=y
 CONFIG_RTC_DRV_MV=y
 CONFIG_RTC_DRV_TEGRA=y