ocfs2: return f_fsid info in ocfs2_statfs()

Currently the f_fsid of struct kstatfs returned from ocfs2_statfs() is
undefined (vfs layer fills in 0 as default). Since in some conditions,
f_fsid value might be used in a (f_fsid, ino) pair to uniquely identify
a file, ocfs2 should return a unique defined f_fsid value from
ocfs2_statfs().

Because uuid_str is the same on big or litlle endian machine, it's
endian consistent to use osb->uuid_str to generate f_fsid value.

Signed-off-by: Coly Li <coly.li@suse.de>
Cc: Sunil Mushran <sunil.mushran@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>