Fix the following gcc warning:

drivers/regulator/qcom_rpm-regulator.c:607:34: warning: ‘pm8921_ftsmps’
defined but not used [-Wunused-const-variable=]
 static const struct qcom_rpm_reg pm8921_ftsmps = {
                                  ^~~~~~~~~~~~~
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200409114026.38383-1-yanaijie@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>