drivers/video/backlight/adp88?0_bl.c: fix resume

Clearing the NSTBY bit in the control register also automatically clears
the BLEN bit.  So we need to make sure to set it again during resume,
otherwise the backlight will stay off.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>