MIPS: Alchemy: remove PB1000 support

Noone seems to have test hardware or care anymore.  Drop PB1000 support
and along with it the old Alchemy PCMCIA socket driver.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
To: linux-mips@linux-mips.org
Cc: netdev@vger.kernel.org
Cc: linux-pcmcia@lists.infradead.org
Patchwork: https://patchwork.linux-mips.org/patch/2881/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>