staging: comedi: add comedi_pcmcia.h

Add a new header that Comedi PCMCIA drivers can include instead of
"comedidev.h".  Currently, it just pulls in <pcmcia/cistpl.h>,
<pcmcia/ds.h> and "comedidev.h", but the plan is to migrate the
PCMCIA-specific stuff from "comedidev.h" here.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>