board: atmel: Use the new PIT timer driver

Use the Atmel PIT timer driver which supports the driver model
and device tree.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
diff --git a/configs/at91sam9g20ek_dataflash_cs0_defconfig b/configs/at91sam9g20ek_dataflash_cs0_defconfig
index 8a7d877..71f8864 100644
--- a/configs/at91sam9g20ek_dataflash_cs0_defconfig
+++ b/configs/at91sam9g20ek_dataflash_cs0_defconfig
@@ -49,5 +49,7 @@
 CONFIG_ATMEL_USART=y
 CONFIG_DM_SPI=y
 CONFIG_ATMEL_SPI=y
+CONFIG_TIMER=y
+CONFIG_ATMEL_PIT_TIMER=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y