[nRF52840] pass received frames to MAC layer regardless PHY or MAC state (#2113)

diff --git a/examples/platforms/nrf52840/radio.c b/examples/platforms/nrf52840/radio.c
index 77c9ae6..cc29e39 100644
--- a/examples/platforms/nrf52840/radio.c
+++ b/examples/platforms/nrf52840/radio.c
@@ -621,13 +621,6 @@
 {
     otRadioFrame *receivedFrame = NULL;
 
-    if (isPendingEventSet(kPendingEventTransmit))
-    {
-        nrf_drv_radio802154_buffer_free_raw(p_data);
-
-        return;
-    }
-
     for (uint32_t i = 0; i < RADIO_RX_BUFFERS; i++)
     {
         if (sReceivedFrames[i].mPsdu == NULL)