drivers: timer: nrf: drop unnecessary counter mask

The RTC COUNTER register doesn't care that it receives a value larger
than it can hold; it'll discard the bits internally.  No need to spend
cycles doing it manually.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
diff --git a/drivers/timer/nrf_rtc_timer.c b/drivers/timer/nrf_rtc_timer.c
index 31484ed..0fafb11 100644
--- a/drivers/timer/nrf_rtc_timer.c
+++ b/drivers/timer/nrf_rtc_timer.c
@@ -31,7 +31,7 @@
 
 static void set_comparator(u32_t cyc)
 {
-	nrf_rtc_cc_set(RTC, 0, cyc & COUNTER_MAX);
+	nrf_rtc_cc_set(RTC, 0, cyc);
 }
 
 static u32_t counter(void)