qtnfmac: fix resource leaks on unsupported iftype error return path

Currently if an unsupported iftype is detected the error return path
does not free the cmd_skb leading to a resource leak. Fix this by
free'ing cmd_skb.

Addresses-Coverity: ("Resource leak")
Fixes: 805b28c0 ("qtnfmac: prepare for AP_VLAN interface type support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200925132224.21638-1-colin.king@canonical.com

drivers/net/wireless/quantenna/qtnfmac/commands.c

@@ -869,6 +869,7 @@ int qtnf_cmd_send_del_intf(struct qtnf_vif *vif)
 	default:
 		pr_warn("VIF%u.%u: unsupported iftype %d\n", vif->mac->macid,
 			vif->vifid, vif->wdev.iftype);
+		dev_kfree_skb(cmd_skb);
 		ret = -EINVAL;
 		goto out;
 	}
@@ -1924,6 +1925,7 @@ int qtnf_cmd_send_change_sta(struct qtnf_vif *vif, const u8 *mac,
 		break;
 	default:
 		pr_err("unsupported iftype %d\n", vif->wdev.iftype);
+		dev_kfree_skb(cmd_skb);
 		ret = -EINVAL;
 		goto out;
 	}