ocfs2: add handler_map array bounds checking

Make the handler_map array as large as the possible value range to avoid
a fencepost error.

[ Utilize alternate method -- Joel ]

Signed-off-by: Tiger Yang <tiger.yang@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>