ocfs2: charge quota for reflinked blocks

When ocfs2 shares blocks from one file to another, it's necessary to
charge that many blocks to the quota because ocfs2 tallies block charges
according to the number of blocks mapped, not the number of physical
blocks used.

Without this patch, reflinking X blocks and then CoWing all of them
causes quota usage to *decrease* by X as seen in generic/305.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>