ACPI: bay: send envp with uevent

Make the bay driver send env information on bay events.

Upon any bay event, we will send the string "BAY_EVENT=%d" along with the
KOBJ_CHANGE, and report the event number.  What the event number means will
be platform specific.  Event 3 is always an eject request, but an insert
may be either event 1, or it may be event 0.  Event 1 may also be a
remove request.  It would be best if you check the number of your event
with udevmonitor before writing any udev scripts for inserting and
removing drive bays.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Cc: Stephan Berberig <s.berberig@arcor.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>