Documentation: ABI: power: Add missing newline at end of file

"git diff" says:

    \ No newline at end of file

after modifying the files.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/ABI/testing/sysfs-power

@@ -300,4 +300,4 @@ Description:
 		attempt.
 
 		Using this sysfs file will override any values that were
-		set using the kernel command line for disk offset.
\ No newline at end of file
+		set using the kernel command line for disk offset.