MIPS: Alchemy: devboards: wire up new PCMCIA driver.

Register the PCMCIA driver on all boards supported by it,
get rid of now-unused pcmcia macros in the board headers
(and subsequently empty pb1100/pb1500 ones).

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>