drm/amdkfd: add debug and runtime enable interface

Introduce the GPU debug operations interface.

For ROCm-GDB to extend the GNU Debugger's ability to inspect the AMD GPU
instruction set, provide the necessary interface to allow the debugger
to HW debug-mode set and query exceptions per HSA queue, process or
device.

The runtime_enable interface coordinates exception handling with the
HSA runtime.

Usage is available in the kern docs at uapi/linux/kfd_ioctl.h.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>