PM: Remove obsolete /sys/devices/.../power/state docs

The /sys/devices/.../power/state files have been gone for a while
now, but I just noticed some documentation that still refers to
them. (Fortunately described as DEPRECATED and WILL REMOVE).

Time to remove that obsolete documentation too ...

Signed-off-by: David Brownell <[e-mail]>
Acked-by: Pavel Machek <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

Documentation/power/devices.txt

···
 to shift to lower voltage settings and reduce the power cost of executing
 a given number of instructions.  (Without voltage adjustment, it's rare
 for cpufreq to save much power; the cost-per-instruction must go down.)
-
-
-/sys/devices/.../power/state files
-==================================
-For now you can also test some of this functionality using sysfs.
-
-	DEPRECATED:  USE "power/state" ONLY FOR DRIVER TESTING, AND
-	AVOID USING dev->power.power_state IN DRIVERS.
-
-	THESE WILL BE REMOVED.  IF THE "power/state" FILE GETS REPLACED,
-	IT WILL BECOME SOMETHING COUPLED TO THE BUS OR DRIVER.
-
-In each device's directory, there is a 'power' directory, which contains
-at least a 'state' file.  The value of this field is effectively boolean,
-PM_EVENT_ON or PM_EVENT_SUSPEND.
-
-   *	Reading from this file displays a value corresponding to
-	the power.power_state.event field.  All nonzero values are
-	displayed as "2", corresponding to a low power state; zero
-	is displayed as "0", corresponding to normal operation.
-
-   *	Writing to this file initiates a transition using the
-   	specified event code number; only '0', '2', and '3' are
-	accepted (without a newline); '2' and '3' are both
-	mapped to PM_EVENT_SUSPEND.
-
-On writes, the PM core relies on that recorded event code and the device/bus
-capabilities to determine whether it uses a partial suspend() or resume()
-sequence to change things so that the recorded event corresponds to the
-numeric parameter.
-
-   -	If the bus requires the irqs-disabled suspend_late()/resume_early()
-	phases, writes fail because those operations are not supported here.
-
-   -	If the recorded value is the expected value, nothing is done.
-
-   -	If the recorded value is nonzero, the device is partially resumed,
-	using the bus.resume() and/or class.resume() methods.
-
-   -	If the target value is nonzero, the device is partially suspended,
-	using the class.suspend() and/or bus.suspend() methods and the
-	PM_EVENT_SUSPEND message.
-
-Drivers have no way to tell whether their suspend() and resume() calls
-have come through the sysfs power/state file or as part of entering a
-system sleep state, except that when accessed through sysfs the normal
-parent/child sequencing rules are ignored.  Drivers (such as bus, bridge,
-or hub drivers) which expose child devices may need to enforce those rules
-on their own.