nilfs2: initialize "struct nilfs_binfo_dat"->bi_pad field

nilfs2: initialize "struct nilfs_binfo_dat"->bi_pad field

nilfs_btree_assign_p() and nilfs_direct_assign_p() are not initializing
"struct nilfs_binfo_dat"->bi_pad field, causing uninit-value reports when
being passed to CRC function.

Link: https://lkml.kernel.org/r/[email protected]
Reported-by: syzbot <[email protected]>
Link: https://syzkaller.appspot.com/bug?extid=048585f3f4227bb2b49b
Reported-by: Dipanjan Das <[email protected]>
Link: https://lkml.kernel.org/r/CANX2M5bVbzRi6zH3PTcNE_31TzerstOXUa9Bay4E6y6dX23_pg@mail.gmail.com
Signed-off-by: Tetsuo Handa <[email protected]>
Signed-off-by: Ryusuke Konishi <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>