nfc: mrvl: mark OF device ID tables as maybe unused

The driver can match either via OF or I2C ID tables.  If OF is disabled,
the table will be unused:

    drivers/nfc/nfcmrvl/spi.c:199:34: warning:
        ‘of_nfcmrvl_spi_match’ defined but not used [-Wunused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210528124200.79655-5-krzysztof.kozlowski@canonical.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/nfc/nfcmrvl/i2c.c

@@ -260,7 +260,7 @@ static int nfcmrvl_i2c_remove(struct i2c_client *client)
 }
 
 
-static const struct of_device_id of_nfcmrvl_i2c_match[] = {
+static const struct of_device_id of_nfcmrvl_i2c_match[] __maybe_unused = {
 	{ .compatible = "marvell,nfc-i2c", },
 	{},
 };

drivers/nfc/nfcmrvl/spi.c

@@ -196,7 +196,7 @@ static int nfcmrvl_spi_remove(struct spi_device *spi)
 	return 0;
 }
 
-static const struct of_device_id of_nfcmrvl_spi_match[] = {
+static const struct of_device_id of_nfcmrvl_spi_match[] __maybe_unused = {
 	{ .compatible = "marvell,nfc-spi", },
 	{},
 };