ARM: at91: at91_dt_defconfig: remove STAGING

There is no driver requiring STAGING so we remove it.

Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>

Author: cristibirsan

arch/arm/configs/at91_dt_defconfig

@@ -219,7 +219,6 @@ CONFIG_RTC_DRV_AT91SAM9=y
 CONFIG_DMADEVICES=y
 CONFIG_AT_HDMAC=y
 CONFIG_AT_XDMAC=y
-CONFIG_STAGING=y
 CONFIG_MICROCHIP_PIT64B=y
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_IIO=y