Revert "backlight: led_bl: Convert to platform remove callback returning void"

This reverts commit 28d49aeb which is
commit c4c4fa57 upstream.

It breaks the Android kernel build and can be brought back in the future
in an safe way if it is really needed.

Bug: 161946584
Change-Id: I64137b01f396e6e66a922f2215038ad9fddb5079
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>