clocksource: dw_apb_timer: Add common DTS glue for dw_apb_timer

Make a common device tree glue for clocksource/dw_apb_timer.
Move mach-picoxcell/time.c to be a generic device tree application
of the dw_apb_timer.

Configure mach-picoxcell to use the dw_apb_timer_of device tree
implementation in drivers/clocksource.

Signed-off-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Dinh Nguyen <dinguyen@altera.com>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a91009c..57eb6ef 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -658,6 +658,7 @@
 	select ARM_VIC
 	select CPU_V6K
 	select DW_APB_TIMER
+	select DW_APB_TIMER_OF
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_GPIO
 	select HAVE_TCM