backlight: convert from legacy pm ops to dev_pm_ops

backlight: convert from legacy pm ops to dev_pm_ops

Convert drivers/video/backlight/class to use dev_pm_ops for power
management and remove Legacy PM ops hooks.  With this change, backlight
class registers suspend/resume callbacks via class->pm (dev_pm_ops)
instead of Legacy class->suspend/resume.  When __device_suspend() runs
call-backs, it will find class->pm ops for the backlight class.

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Cc: Shuah Khan <shuahkhan@gmail.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>