regulator: da9210: Fix W=1 build warning when CONFIG_OF=n

Fix below warning when CONFIG_OF=n:

drivers/regulator/da9210-regulator.c:128:34: warning: ‘da9210_dt_ids’ defined but not used [-Wunused-const-variable=]
  128 | static const struct of_device_id da9210_dt_ids[] = {
      |                                  ^~~~~~~~~~~~~
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Link: https://lore.kernel.org/r/20200821111235.14473a88@xhacker.debianSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/da9210-regulator.c

@@ -125,7 +125,7 @@ static irqreturn_t da9210_irq_handler(int irq, void *data)
  * I2C driver interface functions
  */
 
-static const struct of_device_id da9210_dt_ids[] = {
+static const struct of_device_id __maybe_unused da9210_dt_ids[] = {
 	{ .compatible = "dlg,da9210", },
 	{ }
 };