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/at91sam9n12ek_spiflash_defconfig b/configs/at91sam9n12ek_spiflash_defconfig
index 9fa6894..6279d1f 100644
--- a/configs/at91sam9n12ek_spiflash_defconfig
+++ b/configs/at91sam9n12ek_spiflash_defconfig
@@ -48,6 +48,8 @@
 CONFIG_ATMEL_USART=y
 CONFIG_DM_SPI=y
 CONFIG_ATMEL_SPI=y
+CONFIG_TIMER=y
+CONFIG_ATMEL_PIT_TIMER=y
 CONFIG_USB=y
 CONFIG_DM_USB=y
 CONFIG_USB_STORAGE=y