hw/timer/cmsdk-apb-timer: Correctly identify and set one-shot mode

The CMSDK APB timer is currently always configured as periodic timer.
This results in the following messages when trying to boot Linux.

Timer with delta zero, disabling

If the timer limit set with the RELOAD command is 0, the timer
needs to be enabled as one-shot timer.
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/timer/cmsdk-apb-timer.c

@@ -119,7 +119,7 @@ static void cmsdk_apb_timer_write(void *opaque, hwaddr offset, uint64_t value,
         }
         s->ctrl = value & 0xf;
         if (s->ctrl & R_CTRL_EN_MASK) {
-            ptimer_run(s->timer, 0);
+            ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
         } else {
             ptimer_stop(s->timer);
         }