microblaze: select ARCH_MIGHT_HAVE_PC_PARPORT

Architectures which support CONFIG_PARPORT_PC should select
ARCH_MIGHT_HAVE_PC_PARPORT.

Signed-off-by: Mark Salter <msalter@redhat.com>
CC: Michal Simek <monstr@monstr.eu>
CC: microblaze-uclinux@itee.uq.edu.au