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/mach-picoxcell/common.h b/arch/arm/mach-picoxcell/common.h
index 83d55ab..a65cb02 100644
--- a/arch/arm/mach-picoxcell/common.h
+++ b/arch/arm/mach-picoxcell/common.h
@@ -12,6 +12,6 @@
 
 #include <asm/mach/time.h>
 
-extern struct sys_timer picoxcell_timer;
+extern struct sys_timer dw_apb_timer;
 
 #endif /* __PICOXCELL_COMMON_H__ */