Blackfin: fix gptimer0 clock source compile warning

Some of the clocksource prototypes were updated, but the gptimer0 func was
missed in the process.  Not a big issue as the argument is ignored, but we
should fix the compile warning anyways.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/time-ts.c

@@ -108,7 +108,7 @@ void __init setup_gptimer0(void)
 	enable_gptimers(TIMER0bit);
 }
 
-static cycle_t bfin_read_gptimer0(void)
+static cycle_t bfin_read_gptimer0(struct clocksource *cs)
 {
 	return bfin_read_TIMER0_COUNTER();
 }