NFC: st21nfca: ERR_PTR vs NULL fix
NFC: st21nfca: ERR_PTR vs NULL fix

"skb" can be NULL here but it can't be an ERR_PTR:
- IS_ERR(NULL) return false and skb migth be NULL.
- skb cannot be a ERR_PTR as nfc_hci_send_cmd_async it never using such cast.

!skb is more appropriate at those places.

Reported-by: Dan Carpenter <ff341aa343d564f9e53e9dcb6996be8c04859a66@oracle.com>
Signed-off-by: Christophe Ricard <7fc2cd33e78f60c767c0b054f476a876f109b675@st.com>
Signed-off-by: Samuel Ortiz <0ba86cb3f08bbb861958e54bd3438887adb4263c@linux.intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs