Fix a stupid unbalanced lock bug in the ppc64 hugepage code.  Lead
rapidly to a crash if both CONFIG_HUGETLB_PAGE and CONFIG_PREEMPT were
enabled (even without actually using hugepages at all).
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>