MIPS: PCMCIA: new socket driver for Au1000 demoboards.

New PCMCIA socket driver for all Db/Pb1xxx boards (except Pb1000),
which replaces au1000_db1x00.c and (most of) au1000_pb1x00.c.
Notable improvements:
        - supports Db1000, DB/PB1100/1500/1550/1200.
        - support for carddetect and statuschange IRQs.
        - pcmcia socket mem/io/attr areas and irqs passed through
          platform resource information.
        - doesn't freeze system during card insertion/ejection like
          the one it replaces.
        - boardtype is automatically detected using BCSR ID register.

Run-tested on the DB1200.

Cc: Linux-PCMCIA <linux-pcmcia@lists.infradead.org>
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>