pcmcia/ds.h: introduce helper for pcmcia_driver module boilerplate

Introduce the module_pcmcia_driver() macro which is a convenience macro
for pcmcia driver modules. It is intended to be used by pcmcia drivers
with init/exit sections that do nothing but register/unregister the
pcmcia driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: linux-pcmcia@lists.infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>