qcacmn: Fix a corner case in monitor duplicate WAR

Store last link descriptor for duplicate detection while
skipping invalid MPDUs.

Change-Id: I8ce35c1854875adca6ce59391e302a6fc6d3e28d

dp/wifi3.0/dp_rx_mon_dest.c

@@ -360,6 +360,8 @@ dp_rx_mon_mpdu_pop(struct dp_soc *soc, uint32_t mac_id,
 					drop_mpdu = true;
 					qdf_nbuf_free(msdu);
 					msdu = NULL;
+					dp_pdev->mon_last_linkdesc_paddr =
+						buf_info.paddr;
 					goto next_msdu;
 				}