Revert "ACPI: Ignore _BQC object when registering backlight device"

This reverts commit 7c0ea45b

 which
caused a regression with the backlight being set to off when a laptop
doesn't have a _BQC entry to query the actual backlight value.  The code
blindly then falls back on a value of 0.

See
	http://bugzilla.kernel.org/show_bug.cgi?id=10387
	http://lkml.org/lkml/2008/4/2/366

for details.

Bisected-and-reported-by: Andrey Borzenkov <arvidjaar@mail.ru>
Cc: Zhao Yakui <yakui.zhao@intel.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>