drm/xe: Add process name to devcoredump

drm/xe: Add process name to devcoredump

Process name help us track what application caused the gpug hang, this
is crucial when running several applications at the same time.

v2:
- handle Xe KMD exec_queues without VM

v3:
- use get_pid_task() (suggested by Nirmoy)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240522201203.145403-1-jose.souza@intel.com