drivers/sensors: remove nxsig_notification when signal support is disabled

When all signals are disabled, nxsig_notification is not available and
should not be invoked. Remove the call to avoid build and runtime issues
in no-signal configurations.

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

drivers/sensors/zerocross.c

@@ -81,10 +81,11 @@ struct zc_open_s
   volatile bool do_closing;
 
   /* Zero cross event notification information */
-
+#ifndef CONFIG_DISABLE_ALL_SIGNALS
   pid_t do_pid;
   struct sigevent do_event;
   struct sigwork_s do_work;
+#endif
 };
 
 /****************************************************************************
@@ -175,6 +176,7 @@ static void zerocross_interrupt(FAR const struct zc_lowerhalf_s *lower,
 
   /* Visit each opened reference and notify a zero cross event */
 
+#ifndef CONFIG_DISABLE_ALL_SIGNALS
   for (opriv = priv->zu_open; opriv; opriv = opriv->do_flink)
     {
       /* Signal the waiter */
@@ -183,6 +185,7 @@ static void zerocross_interrupt(FAR const struct zc_lowerhalf_s *lower,
       nxsig_notification(opriv->do_pid, &opriv->do_event,
                          SI_QUEUE, &opriv->do_work);
     }
+#endif
 
   leave_critical_section(flags);
 }
@@ -415,6 +418,7 @@ static int zc_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
        *              failure with the errno value set appropriately.
        */
 
+#ifndef CONFIG_DISABLE_ALL_SIGNALS
       case ZCIOC_REGISTER:
         {
           FAR struct sigevent *event =
@@ -434,6 +438,7 @@ static int zc_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
             }
         }
         break;
+#endif
 
       default:
         {