4ceaf951fb
This change makes it possible to use a POWER Hypervisor virtual terminal device (phyp vty) as a GDB debug port. Similar to the uart debug port, it has to be enabled by setting the hw.uart_phyp.dbgport variable to the vty node of the device tree. Reviewed by: jhibbits Differential Revision: https://reviews.freebsd.org/D22205