nfc: st21nfca: Fix static checker warning

Fix static checker warning:
drivers/nfc/st21nfca/i2c.c:530 st21nfca_hci_i2c_acpi_request_resources()
error: 'gpiod_ena' dereferencing possible ERR_PTR()

Fix so that if no enable gpio can be retrieved an -ENODEV is returned.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: dfa8070d ("nfc: st21nfca: Add support for acpi probing for i2c device.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>