NFC: nci: Fix error check of nci_hci_create_pipe() result

net/nfc/nci/hci.c: In function nci_hci_connect_gate :
net/nfc/nci/hci.c:679: warning: comparison is always false due to limited range of data type

In case of error, nci_hci_create_pipe() returns NCI_HCI_INVALID_PIPE,
and not a negative error code.

Correct the check to fix this.

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>