clocksource: pass clocksource to read() callback

Pass clocksource pointer to the read() callback for clocksources.  This
allows us to share the callback between multiple instances.

[hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm/mach-versatile/core.c

@@ -948,7 +948,7 @@ static struct irqaction versatile_timer_irq = {
 	.handler	= versatile_timer_interrupt,
 };
 
-static cycle_t versatile_get_cycles(void)
+static cycle_t versatile_get_cycles(struct clocksource *cs)
 {
 	return ~readl(TIMER3_VA_BASE + TIMER_VALUE);
 }