pcmcia: remove unused bulkmem.h

The code in include/pcmcia/bulkmem.h was only kept for compatibility reasons.
Therefore, move the remaining region_info_t definition to ds.h

[linux@dominikbrodowski.net: do not modify the IOCTL, move definition to
 ds.h, and update changelog]
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>