qcacmn: Add rx_errors stats

Update rx error stats. It is a summation of below failures:
 - desc_alloc_failure [No free desc available]
 - csum error [IP/TCP_UDP]
These failure stats are updated at pdev level and no need
to aggregate this.Directly add at pdev level and export.

Change-Id: I0a5fa8f972babf092163f3cb2d0093547ded4877
CRs-Fixed: 2496037

dp/wifi3.0/dp_main.c

@@ -6830,6 +6830,12 @@ static void dp_pdev_getstats(void *pdev_handle,
 	stats->rx_bytes = pdev->stats.rx.unicast.bytes +
 		pdev->stats.rx.multicast.bytes +
 		pdev->stats.rx.bcast.bytes;
+	stats->rx_errors = pdev->stats.err.desc_alloc_fail +
+		pdev->stats.err.ip_csum_err +
+		pdev->stats.err.tcp_udp_csum_err +
+		pdev->stats.rx.err. mic_err +
+		pdev->stats.rx.err. decrypt_err +
+		pdev->stats.rx.err. fcserr;
 }
 
 /**