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/at91sam9rlek_nandflash_defconfig b/configs/at91sam9rlek_nandflash_defconfig
index 7a756f6..4bdd1c0 100644
--- a/configs/at91sam9rlek_nandflash_defconfig
+++ b/configs/at91sam9rlek_nandflash_defconfig
@@ -52,4 +52,6 @@
 CONFIG_ATMEL_USART=y
 CONFIG_DM_SPI=y
 CONFIG_ATMEL_SPI=y
+CONFIG_TIMER=y
+CONFIG_ATMEL_PIT_TIMER=y
 CONFIG_LCD=y