Fixes for OpenBSD templates. The obsd55amd64iso template had the img_grub_cfg line identical to iso_grub_cfg line and obsd56amd64iso should have "boot bsd" rather than "boot bsd.mp" as part of img_grub_cfg line if vm_cpus > 1 due to the fact that the OpenBSD installer will name bsd.mp as bsd if it detects > 1 cpu.