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>

drivers/nfc/st21nfca/i2c.c

@@ -524,8 +524,10 @@ static int st21nfca_hci_i2c_acpi_request_resources(struct i2c_client *client)
 	/* Get EN GPIO from ACPI */
 	gpiod_ena = devm_gpiod_get_index(dev, ST21NFCA_GPIO_NAME_EN, 1,
 					 GPIOD_OUT_LOW);
-	if (!IS_ERR(gpiod_ena))
-		phy->gpio_ena = desc_to_gpio(gpiod_ena);
+	if (!IS_ERR(gpiod_ena)) {
+		nfc_err(dev, "Unable to get ENABLE GPIO\n");
+		return -ENODEV;
+	}
 
 	phy->gpio_ena = desc_to_gpio(gpiod_ena);