nfc: st-nci: mark ACPI and OF device ID tables as maybe unused

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

    drivers/nfc/st-nci/spi.c:296:34: warning:
        ‘of_st_nci_spi_match’ defined but not used [-Wunused-const-variable=]
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210528124200.79655-10-krzysztof.kozlowski@canonical.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/nfc/st-nci/i2c.c

@@ -274,14 +274,14 @@ static const struct i2c_device_id st_nci_i2c_id_table[] = {
 };
 MODULE_DEVICE_TABLE(i2c, st_nci_i2c_id_table);
 
-static const struct acpi_device_id st_nci_i2c_acpi_match[] = {
+static const struct acpi_device_id st_nci_i2c_acpi_match[] __maybe_unused = {
 	{"SMO2101"},
 	{"SMO2102"},
 	{}
 };
 MODULE_DEVICE_TABLE(acpi, st_nci_i2c_acpi_match);
 
-static const struct of_device_id of_st_nci_i2c_match[] = {
+static const struct of_device_id of_st_nci_i2c_match[] __maybe_unused = {
 	{ .compatible = "st,st21nfcb-i2c", },
 	{ .compatible = "st,st21nfcb_i2c", },
 	{ .compatible = "st,st21nfcc-i2c", },

drivers/nfc/st-nci/spi.c

@@ -287,13 +287,13 @@ static struct spi_device_id st_nci_spi_id_table[] = {
 };
 MODULE_DEVICE_TABLE(spi, st_nci_spi_id_table);
 
-static const struct acpi_device_id st_nci_spi_acpi_match[] = {
+static const struct acpi_device_id st_nci_spi_acpi_match[] __maybe_unused = {
 	{"SMO2101", 0},
 	{}
 };
 MODULE_DEVICE_TABLE(acpi, st_nci_spi_acpi_match);
 
-static const struct of_device_id of_st_nci_spi_match[] = {
+static const struct of_device_id of_st_nci_spi_match[] __maybe_unused = {
 	{ .compatible = "st,st21nfcb-spi", },
 	{}
 };