ARM: mach-realview and mach-versatile: retire custom LED code

This replaces the custom LED trigger code in mach-realview with
some overarching platform code for the plat-versatile family that
will lock down LEDs 2 thru 5 for CPU activity indication. The
day we have 8 core ARM systems the plat-versatile code will have
to become more elaborate.

Tested on RealView PB11MPCore by invoking four different CPU
hogs (yes > /dev/null&) and see the LEDs go on one at a time.
They all go off as the hogs are killed. Tested on the PB1176
as well - just one activity led (led 2) goes on and off with
CPU activity.

(bryan.wu@canonical.com: use ledtrig-cpu instead of ledtrig-arm-cpu)

Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>

arch/arm/mach-versatile/core.c

@@ -37,7 +37,6 @@
 #include <linux/mtd/physmap.h>
 
 #include <asm/irq.h>
-#include <asm/leds.h>
 #include <asm/hardware/arm_timer.h>
 #include <asm/hardware/icst.h>
 #include <asm/hardware/vic.h>
@@ -763,10 +762,6 @@ void __init versatile_init(void)
 		struct amba_device *d = amba_devs[i];
 		amba_device_register(d, &iomem_resource);
 	}
-
-#ifdef CONFIG_LEDS
-	leds_event = versatile_leds_event;
-#endif
 }
 
 /*