ocfs2: fix possible uninitialized variable access

In ocfs2_local_alloc_find_clear_bits and ocfs2_get_dentry, variable
numfound and set may be uninitialized and then used in tracepoint.  In
ocfs2_xattr_block_get and ocfs2_delete_xattr_in_bucket, variable block_off
and xv may be uninitialized and then used in the following logic due to
unchecked return value.

This patch fixes these possible issues.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>