core: Fix use after free in case of command transmit failure

Fixes the following-

[ 2691.143973]ipa ipa3_rmnet_ctl_xmit:474 rmnet_ctl tx queue full
[ 2691.144001]Failed to send to rmnet ctl
[ 2691.144020]Unable to handle kernel NULL pointer dereference at
              virtual address 0000000000000000
[ 2691.144087]Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 2691.145120]Workqueue: rmnet_powersave_work qmi_rmnet_check_stats_2.cfi_jt
              [rmnet_core]
[ 2691.145147]pc : __skb_ext_put+0x24/0x1c0
[ 2691.145156]lr : skb_release_head_state+0x108/0x1bc
[ 2691.145317]__skb_ext_put+0x24/0x1c0
[ 2691.145324]skb_release_head_state+0x108/0x1bc
[ 2691.145331]kfree_skb+0x7c/0x4d0
[ 2691.145445]rmnet_qmap_send+0x128/0x258 [rmnet_core]
[ 2691.145534]dfc_qmap_set_powersave+0x154/0x2bc [rmnet_core]
[ 2691.145624]qmi_rmnet_check_stats_2+0xb4/0x488 [rmnet_core]
[ 2691.145636]process_one_work+0x248/0x820
[ 2691.145642]worker_thread+0x438/0xbd8
[ 2691.145649]kthread+0x150/0x200
[ 2691.145656]ret_from_fork+0x10/0x30

CRs-Fixed: 3023614
Change-Id: Ibb6063ad41a1b9407b4735dc6cf688038b352088
Signed-off-by: Subash Abhinov Kasiviswanathan <[email protected]>

core/rmnet_qmap.c

@@ -38,7 +38,6 @@ int rmnet_qmap_send(struct sk_buff *skb, u8 ch, bool flush)
 
 	if (rmnet_ctl->send(rmnet_ctl_handle, skb)) {
 		pr_err("Failed to send to rmnet ctl\n");
-		kfree_skb(skb);
 		return -ECOMM;
 	}