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