qcacmn: wifi DP TX optimization for RMNET pkts

pkts from rmnet device are sent as SG, we see poor
throughput when transmitting these SG frames using
an MSDU extension descriptor. to resolve this issue
we identify if the frame is from RMNET device and if so
copy the headers from skb linear address to the frag
address and provide the frag address to HW for transmission

CRs-Fixed: 3337822
Change-Id: Ic1b7d9f861dcd4f838509772c45e47d3917fc59f

dp/wifi3.0/dp_tx.h

@@ -60,6 +60,7 @@
 #define DP_TX_DESC_FLAG_TX_COMP_ERR	0x1000
 #define DP_TX_DESC_FLAG_FLUSH		0x2000
 #define DP_TX_DESC_FLAG_TRAFFIC_END_IND	0x4000
+#define DP_TX_DESC_FLAG_RMNET		0x8000
 /*
  * Since the Tx descriptor flag is of only 16-bit and no more bit is free for
  * any new flag, therefore for time being overloading PPEDS flag with that of
@@ -224,6 +225,10 @@ struct dp_tx_msdu_info_s {
 #ifdef WLAN_DP_FEATURE_SW_LATENCY_MGR
 	uint8_t skip_hp_update;
 #endif
+#ifdef QCA_DP_TX_RMNET_OPTIMIZATION
+	uint16_t buf_len;
+	uint8_t *payload_addr;
+#endif
 };
 
 #ifndef QCA_HOST_MODE_WIFI_DISABLED