ocfs2: Fix compilation warning for fs/ocfs2/xattr.c

gcc 4.4.1 generates the following build warning on i386:

CC [M]  fs/ocfs2/xattr.o
fs/ocfs2/xattr.c: In function ‘ocfs2_xattr_block_get’:
fs/ocfs2/xattr.c:1055: warning: ‘block_off’ may be used uninitialized in this function

The following fix is based on a similar approach by David Howells
few days back: http://lkml.org/lkml/2009/7/9/109

,

Signed-off-by: Subrata <Modak&lt;subrata@linux.vnet.ibm.com&gt;,>
Signed-off-by: Joel Becker <joel.becker@oracle.com>