drivers/video/backlight/platform_lcd.c: remove unnecessary ifdefs

When the macro such as SIMPLE_DEV_PM_OPS is used, there is no need to
use '#ifdef CONFIG_PM' to prevent build error.  Thus, this patch removes
unnecessary ifdefs.

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>