If no BAT is given to setbat(), select an available BAT.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a212bd36fbd6179e0929b6c727febc35132ac25c.1568665466.git.christophe.leroy@c-s.fr