Add a machine driver suitable for the AC97 part on the DB1000/DB1500/DB1100
boards.

Run-tested on DB1500.
Signed-off-by: NManuel Lauss <manuel.lauss@googlemail.com>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Acked-by: NLiam Girdwood <lrg@ti.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>