ahci: Add some MMIO debug printfs These are useful for bringup of AHCI. Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 517ba413dce7deb4ab17c0cc1e8bbdaaace2a0db.1445917756.git.crosthwaite.peter@gmail.com Signed-off-by: John Snow <jsnow@redhat.com>