driver: timer: Add the Atmel PIT timer driver

Add the new Atmel PIT timer driver, which supports the driver model
and device tree.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
diff --git a/arch/arm/mach-at91/arm926ejs/Makefile b/arch/arm/mach-at91/arm926ejs/Makefile
index 624ccd7..dc935fd 100644
--- a/arch/arm/mach-at91/arm926ejs/Makefile
+++ b/arch/arm/mach-at91/arm926ejs/Makefile
@@ -22,7 +22,9 @@
 obj-y += clock.o
 obj-y += cpu.o
 obj-y	+= reset.o
+ifeq ($(CONFIG_ATMEL_PIT_TIMER),)
 obj-y	+= timer.o
+endif
 
 ifndef CONFIG_SKIP_LOWLEVEL_INIT
 obj-y	+= lowlevel_init.o