Keyboard backlight control for some Vaio Fit models

SVF1521P6EW, SVF1521DCXW, SVF13N1L2ES and likely most SVF*.
do not expose separate timeout controls in auto mode.

Signed-off-by: Dominik Matta <dominik@matta.sk>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>