nfc: st95hf: 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/st95hf/core.c:1059:34: warning:
        ‘st95hf_spi_of_match’ defined but not used [-Wunused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210528124200.79655-12-krzysztof.kozlowski@canonical.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/nfc/st95hf/core.c

@@ -1056,7 +1056,7 @@ static const struct spi_device_id st95hf_id[] = {
 };
 MODULE_DEVICE_TABLE(spi, st95hf_id);
 
-static const struct of_device_id st95hf_spi_of_match[] = {
+static const struct of_device_id st95hf_spi_of_match[] __maybe_unused = {
         { .compatible = "st,st95hf" },
         { },
 };