hwmon: (pmbus/core) Add helper macro to define single pmbus regulator

The bindings for single instance regulator should be named with no instance
(e.g., buck not buck0). Introduce a new helper macro to define the single pmbus
regulator.

Signed-off-by: Saravanan Sekar <saravanan@linumiz.com>
Link: https://lore.kernel.org/r/20231011164754.449399-4-saravanan@linumiz.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: ssekar15

drivers/hwmon/pmbus/pmbus.h

@@ -489,6 +489,21 @@ extern const struct regulator_ops pmbus_regulator_ops;
 
 #define PMBUS_REGULATOR(_name, _id)   PMBUS_REGULATOR_STEP(_name, _id, 0, 0, 0)
 
+#define PMBUS_REGULATOR_STEP_ONE(_name, _voltages, _step, _min_uV)  \
+	{							\
+		.name = (_name),				\
+		.of_match = of_match_ptr(_name),		\
+		.regulators_node = of_match_ptr("regulators"),	\
+		.ops = &pmbus_regulator_ops,			\
+		.type = REGULATOR_VOLTAGE,			\
+		.owner = THIS_MODULE,				\
+		.n_voltages = _voltages,			\
+		.uV_step = _step,				\
+		.min_uV = _min_uV,				\
+	}
+
+#define PMBUS_REGULATOR_ONE(_name)   PMBUS_REGULATOR_STEP_ONE(_name, 0, 0, 0)
+
 /* Function declarations */
 
 void pmbus_clear_cache(struct i2c_client *client);