rfkill: document the rfkill struct locking (v2)

 * @user_claim_unsupported: Whether the hardware supports exclusive

 *	RF-kill control by userspace. Set this before registering.

 * @user_claim: Set when the switch is controlled exlusively by userspace.

 * @mutex: Guards switch state transitions

 * @mutex: Guards switch state transitions.  It serializes callbacks

 *	and also protects the state.

 * @data: Pointer to the RF button drivers private data which will be

 *	passed along when toggling radio state.

 * @toggle_radio(): Mandatory handler to control state of the radio.

	const char *name;

	enum rfkill_type type;

	enum rfkill_state state;

	bool user_claim_unsupported;

	bool user_claim;

	/* the mutex serializes callbacks and also protects

	 * the state */

	struct mutex mutex;

	enum rfkill_state state;

	void *data;

	int (*toggle_radio)(void *data, enum rfkill_state state);

	int (*get_state)(void *data, enum rfkill_state *state);