backlight: tosa: use devm_gpio_request_one

backlight: tosa: use devm_gpio_request_one

By using devm_gpio_request_one it is possible to set the direction and
initial value in one shot.  Thus, using devm_gpio_request_one can make the
code simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>