regulator: Add units to limit documentation

The documentation for limits used at protection level setting
did not mention the units. Fix the units in documentation to
match values passed in from device-tree (uV, uA, Kelvin) to
avoid confusion.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/111114aca991e41e49a32f89b74e95285f07c1e3.1637233864.git.matti.vaittinen@fi.rohmeurope.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/driver.h

@@ -101,11 +101,13 @@ enum regulator_detection_severity {
  *		is requested.
  * @set_over_voltage_protection: Support enabling of and setting limits for over
  *	voltage situation detection. Detection can be configured for same
- *	severities as over current protection.
+ *	severities as over current protection. Units of uV.
  * @set_under_voltage_protection: Support enabling of and setting limits for
- *	under situation detection.
+ *	under voltage situation detection. Detection can be configured for same
+ *	severities as over current protection. Units of uV.
  * @set_thermal_protection: Support enabling of and setting limits for over
- *	temperature situation detection.
+ *	temperature situation detection.Detection can be configured for same
+ *	severities as over current protection. Units of degree Kelvin.
  *
  * @set_active_discharge: Set active discharge enable/disable of regulators.
  *