Fix the following gcc warning:

drivers/regulator/ab8500.c:195:27: warning: ‘ldo_vdmic_voltages’ defined
but not used [-Wunused-const-variable=]
 static const unsigned int ldo_vdmic_voltages[] = {
                           ^~~~~~~~~~~~~~~~~~
drivers/regulator/ab8500.c:169:27: warning: ‘fixed_3300000_voltage’
defined but not used [-Wunused-const-variable=]
 static const unsigned int fixed_3300000_voltage[] = {
                           ^~~~~~~~~~~~~~~~~~~~~
drivers/regulator/ab8500.c:142:27: warning: ‘ldo_sdio_voltages’ defined
but not used [-Wunused-const-variable=]
 static const unsigned int ldo_sdio_voltages[] = {
                           ^~~~~~~~~~~~~~~~~
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200410073343.39031-1-yanaijie@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>