soc: qcom: gsbi: mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  drivers/soc/qcom/qcom_gsbi.c:117:34: error: ‘tcsr_dt_match’ defined but not used [-Werror=unused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230310214413.275054-1-krzysztof.kozlowski@linaro.org

drivers/soc/qcom/qcom_gsbi.c

@@ -114,7 +114,7 @@ struct gsbi_info {
 	struct regmap *tcsr;
 };
 
-static const struct of_device_id tcsr_dt_match[] = {
+static const struct of_device_id tcsr_dt_match[] __maybe_unused = {
 	{ .compatible = "qcom,tcsr-ipq8064", .data = &config_ipq8064},
 	{ .compatible = "qcom,tcsr-apq8064", .data = &config_apq8064},
 	{ .compatible = "qcom,tcsr-msm8960", .data = &config_msm8960},