m48t59: use rtc_clock for alarm timer

This lets the RTC get adjustments from the host NTP client.
The watchdog still uses the vm_clock.  The previous behavior is
available with "-rtc clock=vm".

Cc: Andreas Färber <afaerber@suse.de>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/m48t59.c

@@ -126,7 +126,7 @@ static void alarm_cb (void *opaque)
         /* Repeat once a second */
         next_time = 1;
     }
-    qemu_mod_timer(NVRAM->alrm_timer, qemu_get_clock_ns(vm_clock) +
+    qemu_mod_timer(NVRAM->alrm_timer, qemu_get_clock_ns(rtc_clock) +
                     next_time * 1000);
     qemu_set_irq(NVRAM->IRQ, 0);
 }
@@ -687,7 +687,7 @@ static void m48t59_init_common(M48t59State *s)
 {
     s->buffer = g_malloc0(s->size);
     if (s->type == 59) {
-        s->alrm_timer = qemu_new_timer_ns(vm_clock, &alarm_cb, s);
+        s->alrm_timer = qemu_new_timer_ns(rtc_clock, &alarm_cb, s);
         s->wd_timer = qemu_new_timer_ns(vm_clock, &watchdog_cb, s);
     }
     qemu_get_timedate(&s->alarm, 0);