Revert "ACPICA: fix AML mutex re-entrancy"

This reverts commit c0d127b5

.

These changes to AML locking were made to allow
Notify handlers to be called on the stack
and not deadlock.  However, that scheme turns
out to be flawed and was reverted by the previous commit,
so this commit restores the locking to it previous design.

Signed-off-by: Len Brown <len.brown@intel.com>