regulator: mp886x: use "mps,switch-frequency-hz"

As Rob suggested, use the "mps,switch-frequency-hz" instead of the
"mps,switch-frequency" for switch frequency. Fortunately, the switch
frequency support isn't released, so we can modify it now without
any concern.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/20200824102402.4047fa5f@xhacker.debianSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/mp886x.txt

@@ -10,7 +10,7 @@ Required properties:
   values R1 and R2 of the feedback voltage divider in kilo ohms.
 
 Optional properties:
-- mps,switch-frequency: The valid switch frequency in Hertz. Available values
+- mps,switch-frequency-hz: The valid switch frequency in Hertz. Available values
   are: 500000, 750000, 1000000, 1250000, 1500000
 
 Any property defined as part of the core regulator binding, defined in

drivers/regulator/mp886x.c

@@ -349,7 +349,7 @@ static int mp886x_i2c_probe(struct i2c_client *client)
 	config.driver_data = di;
 	config.of_node = np;
 
-	if (!of_property_read_u32(np, "mps,switch-frequency", &freq))
+	if (!of_property_read_u32(np, "mps,switch-frequency-hz", &freq))
 		mp886x_set_switch_freq(di, regmap, freq);
 
 	ret = mp886x_regulator_register(di, &config);