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/20230326152146.15872-1-konishi.ryusuke@gmail.com
Reported-by: syzbot <syzbot+048585f3f4227bb2b49b@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?extid=048585f3f4227bb2b49b
Reported-by: Dipanjan Das <mail.dipanjan.das@gmail.com>
Link: https://lkml.kernel.org/r/CANX2M5bVbzRi6zH3PTcNE_31TzerstOXUa9Bay4E6y6dX23_pg@mail.gmail.com
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>