video: backlight: tosa: Use GPIO lookup table

The driver should not require a machine specific header. Change
it to pass the GPIO line through a lookup table, and move the
timing generator definitions into the drivers itself.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>