power: charger-manager: comment spelling fixes

By accident I stumbled over a few misspelled words in the
charger-manager header file which this patch fixes. Namely:
- Extcon rather than Exton
- constraint rather than constratint
- existence rather than existance
- difference rather than diffential

While at it also add a missing space before a closing comment star
forward-slash.

Signed-off-by: Marcel Ziswiler <[e-mail]>
Signed-off-by: Sebastian Reichel <[e-mail]>

include/linux/power/charger-manager.h

···
 	const char *extcon_name;
 	const char *name;
 
-	/* The charger-manager use Exton framework*/
+	/* The charger-manager use Extcon framework */
 	struct extcon_specific_cable_nb extcon_dev;
 	struct work_struct wq;
 	struct notifier_block nb;
···
  *	the charger will be maintained with disabled state.
  * @cables:
  *	the array of charger cables to enable/disable charger
- *	and set current limit according to constratint data of
+ *	and set current limit according to constraint data of
  *	struct charger_cable if only charger cable included
  *	in the array of charger cables is attached/detached.
  * @num_cables: the number of charger cables.
···
  * @polling_interval_ms: interval in millisecond at which
  *	charger manager will monitor battery health
  * @battery_present:
- *	Specify where information for existance of battery can be obtained
+ *	Specify where information for existence of battery can be obtained
  * @psy_charger_stat: the names of power-supply for chargers
  * @num_charger_regulator: the number of entries in charger_regulators
  * @charger_regulators: array of charger regulators
···
  * @thermal_zone : the name of thermal zone for battery
  * @temp_min : Minimum battery temperature for charging.
  * @temp_max : Maximum battery temperature for charging.
- * @temp_diff : Temperature diffential to restart charging.
+ * @temp_diff : Temperature difference to restart charging.
  * @measure_battery_temp:
  *	true: measure battery temperature
  *	false: measure ambient temperature