backlight: corgi_lcd: use lcd_get_data instead of dev_get_drvdata

Use the wrapper function for getting the driver data using lcd_device
instead of using dev_get_drvdata with &ld->dev, so we can directly pass a
struct lcd_device.

Signed-off-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>