regulator: max77826: Fix W=1 build warning when CONFIG_OF=n

Fix below warning when CONFIG_OF=n:

drivers/regulator/max77826-regulator.c:277:34: warning: ‘max77826_of_match’ defined but not used [-Wunused-const-variable=]
  277 | static const struct of_device_id max77826_of_match[] = {
      |                                  ^~~~~~~~~~~~~~~~~
Signed-off-by: NJisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/20200821111631.4e799c86@xhacker.debianSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/regulator/max77826-regulator.c

@@ -274,7 +274,7 @@ static int max77826_i2c_probe(struct i2c_client *client)
 	return max77826_read_device_id(regmap, dev);
 }
 
-static const struct of_device_id max77826_of_match[] = {
+static const struct of_device_id __maybe_unused max77826_of_match[] = {
 	{ .compatible = "maxim,max77826" },
 	{ /* sentinel */ }
 };