nfc: s3fwrn5: use signed integer for parsing GPIO numbers

GPIOs - as returned by of_get_named_gpio() and used by the gpiolib - are
signed integers, where negative number indicates error.  The return
value of of_get_named_gpio() should not be assigned to an unsigned int
because in case of !CONFIG_GPIOLIB such number would be a valid GPIO.

Fixes: c04c674f ("nfc: s3fwrn5: Add driver for Samsung S3FWRN5 NFC Chip")
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201123162351.209100-1-krzk@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/nfc/s3fwrn5/i2c.c

@@ -26,8 +26,8 @@ struct s3fwrn5_i2c_phy {
 	struct i2c_client *i2c_dev;
 	struct nci_dev *ndev;
 
-	unsigned int gpio_en;
-	unsigned int gpio_fw_wake;
+	int gpio_en;
+	int gpio_fw_wake;
 
 	struct mutex mutex;