ocfs2: drop the BLKDEV_IFL_WAIT flag

Commit dd3932ed ("block: remove BLKDEV_IFL_WAIT") had removed the
flag argument to blkdev_issue_flush(), but the ocfs2 merge brought in a
new one.  It didn't cause a merge conflict, so the merges silently
worked out fine, but the result didn't actually compile.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>