NFC: digital: fix possible memory leak in digital_in_send_sdd_req()

'skb' is allocated in digital_in_send_sdd_req(), but not free when
digital_in_send_cmd() failed, which will cause memory leak. Fix it
by freeing 'skb' if digital_in_send_cmd() return failed.

Fixes: 2c66daec ("NFC Digital: Add NFC-A technology support")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/nfc/digital_technology.c

@@ -465,8 +465,12 @@ static int digital_in_send_sdd_req(struct nfc_digital_dev *ddev,
 	skb_put_u8(skb, sel_cmd);
 	skb_put_u8(skb, DIGITAL_SDD_REQ_SEL_PAR);
 
-	return digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sdd_res,
+	rc = digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sdd_res,
 				 target);
+	if (rc)
+		kfree_skb(skb);
+
+	return rc;
 }
 
 static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg,