drivers/video/backlight/platform_lcd.c: introduce probe callback

drivers/video/backlight/platform_lcd.c: introduce probe callback

Platform LCD devices may need to do some device-specific initialization
before they can be used (regulator or GPIO setup, for example), but
currently the driver does not support any way of doing this.  This patch
adds a probe() callback to plat_lcd_data which platform LCD devices can
set to indicate that device-specific initialization is needed.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>