drm/i915: Don't show the blank process name for internal/simulated errors

For a simulated preemption reset, we don't populate the request and so
do not fill in the guilty context name.

[   79.991294] i915 0000:00:02.0: GPU HANG: ecode 9:1:e757fefe, in  [0]

Just don't mention the empty string in the logs!

Fixes: 742379c0 ("drm/i915: Start chopping up the GPU error capture")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200121132107.267709-1-chris@chris-wilson.co.uk


(cherry picked from commit 29baf3ae)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>