Add support for handle 0x0143 (Vaio SA/SB/SC, CA/CB) and rework the code
to be hable to support different handles for the keyboard backlight
function.

[malattia@linux.it: group function specific variables in a struct]
Signed-off-by: NMarco Chiappero <marco@absence.it>
Signed-off-by: NMattia Dongili <malattia@linux.it>
Signed-off-by: NMatthew Garrett <mjg@redhat.com>