xtensa:fix the incompatible pointer type warning in time.c

Fix the definition of the function ccount_read to be compatible
to the member read of the structure clocksource.

Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index ac62f9c..19b32a0 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -31,7 +31,7 @@
 unsigned long nsec_per_ccount;		/* nsec per ccount increment */
 #endif
 
-static cycle_t ccount_read(void)
+static cycle_t ccount_read(struct clocksource *cs)
 {
 	return (cycle_t)get_ccount();
 }