ocfs2: Use GFP_NOFS in kmalloc during localalloc window move

kmalloc() during a localalloc window move can trigger the mm to prune
the dcache which inturn can trigger the fs to delete an inode causing
it start a recursive transaction.

The fix also makes the change in kmalloc during localalloc shutdown
just to be safe.

Fixes oss bugzilla#901
http://oss.oracle.com/bugzilla/show_bug.cgi?id=901

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>