hwmon: (pmbus) Introduce PMBUS symbol namespace

Exported pmbus symbols are only supposed to be used from PMBus code.
Introduce PMBUS symbol namespace to prevent misuse from other code.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/drivers/hwmon/pmbus/ir38064.c b/drivers/hwmon/pmbus/ir38064.c
index 46f17c4..1fb7f124 100644
--- a/drivers/hwmon/pmbus/ir38064.c
+++ b/drivers/hwmon/pmbus/ir38064.c
@@ -61,3 +61,4 @@ module_i2c_driver(ir38064_driver);
 MODULE_AUTHOR("Maxim Sloyko <maxims@google.com>");
 MODULE_DESCRIPTION("PMBus driver for Infineon IR38064");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(PMBUS);