[nrf fromtree] drivers: nrf_wifi: Fix TX drop statistics

In case FMAC API fails, increment the TX drop counter, helpful in
debug.

Signed-off-by: Chaitanya Tata <[email protected]>
(cherry picked from commit e728f80)

Author: krish2718

drivers/wifi/nrf_wifi/src/net_if.c

@@ -429,6 +429,10 @@ int nrf_wifi_if_send(const struct device *dev,
 #ifdef CONFIG_NRF70_RAW_DATA_TX
 	}
 #endif /* CONFIG_NRF70_RAW_DATA_TX */
+	if (ret == NRF_WIFI_STATUS_FAIL) {
+		/* FMAC API takes care of freeing the nbuf */
+		host_stats->total_tx_drop_pkts++;
+	}
 	goto unlock;
 drop:
 	if (host_stats != NULL) {