AP_IOMCU: use more efficient read API for rcin

libraries/AP_IOMCU/iofirmware/iofirmware.cpp

@@ -301,9 +301,7 @@ void AP_IOMCU_FW::rcin_update()
     if (hal.rcin->new_input()) {
         rc_input.count = hal.rcin->num_channels();
         rc_input.flags_rc_ok = true;
-        for (uint8_t i = 0; i < IOMCU_MAX_CHANNELS; i++) {
-            rc_input.pwm[i] = hal.rcin->read(i);
-        }
+        hal.rcin->read(rc_input.pwm, IOMCU_MAX_CHANNELS);
         rc_last_input_ms = last_ms;
         rc_input.rc_protocol = (uint16_t)AP::RC().protocol_detected();
     } else if (last_ms - rc_last_input_ms > 200U) {
@@ -315,6 +313,7 @@ void AP_IOMCU_FW::rcin_update()
     }
     if (update_default_rate) {
         hal.rcout->set_default_rate(reg_setup.pwm_defaultrate);
+        update_default_rate = false;
     }
 
     bool old_override = override_active;