pxa/hx4700: Remove pcmcia platform_device structure

The existing pcmcia platform_device structure is not used and is not needed by
the pending hx4700 PCMCIA/CF support. So let's remove it.

Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>