qcacmn: Memory stats for SKB usage and Tx desc cnt in datapath

Add sysfs node for DP level memory stats:
/sys/kernel/wifi/wlan/wlan_dp_mem_stats
These include Tx, Rx SKB memory allocated, Tx/Rx
buffer count, outstanding Tx desc count.

Change-Id: I839a5f2ec4e763ca11cdea2093368ca6dc52d8cf
CRs-Fixed: 2724460

dp/wifi3.0/dp_ipa.c

@@ -309,6 +309,8 @@ static void dp_tx_ipa_uc_detach(struct dp_soc *soc, struct dp_pdev *pdev)
 		if (!nbuf)
 			continue;
 		qdf_nbuf_unmap_single(soc->osdev, nbuf, QDF_DMA_BIDIRECTIONAL);
+		qdf_mem_dp_tx_skb_cnt_dec();
+		qdf_mem_dp_tx_skb_dec(qdf_nbuf_get_data_len(nbuf));
 		qdf_nbuf_free(nbuf);
 		soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned[idx] =
 						(void *)NULL;
@@ -442,6 +444,8 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 		qdf_nbuf_map_single(soc->osdev, nbuf,
 				    QDF_DMA_BIDIRECTIONAL);
 		buffer_paddr = qdf_nbuf_get_frag_paddr(nbuf, 0);
+		qdf_mem_dp_tx_skb_cnt_inc();
+		qdf_mem_dp_tx_skb_inc(qdf_nbuf_get_data_len(nbuf));
 
 		paddr_lo = ((uint64_t)buffer_paddr & 0x00000000ffffffff);
 		paddr_hi = ((uint64_t)buffer_paddr & 0x0000001f00000000) >> 32;