hwmon: pmbus: Reduce clear fault page invocations

hwmon: pmbus: Reduce clear fault page invocations

Observing I2C traffic revealed consecutive transmission of CLEAR_FAULT
commands. While this doesn't cause issues, it extends driver probe time.

Avoid invoking pmbus_clear_fault_page for virtual registers, as they're
managed by the driver, not the chip.

TEST: Verified using an I2C bus analyzer that only one CLEAR_FAULT
      command is send instead 5 in a row.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Link: https://lore.kernel.org/r/20230817092527.808631-1-Naresh.Solanki@9elements.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>