staging: unisys: remove parahotplug proc entry

Remove the parahotplug proc code entirely in preparation for replacement with
sysfs entries. Since visorchipset_proc_read_writeonly() is orphaned by the
removal, it is removed as well.

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>