Also update references to sony-laptop.txt in Kconfig.
Signed-off-by: NCarlos Corbacho <carlos@strangeworlds.co.uk>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
CC: Mattia Dongili <malattia@linux.it>
Signed-off-by: NLen Brown <len.brown@intel.com>

Signed-off-by: NMattia Dongili <malattia@linux.it>
Signed-off-by: NLen Brown <len.brown@intel.com>

Update documentation to be consistent with current implementation
(backlight subsys and platform_device).
Signed-off-by: NMattia Dongili <malattia@linux.it>
Signed-off-by: NLen Brown <len.brown@intel.com>