drm/i915: Use the i915_device name for identifying our, request fences

[Colin Ian King]

Hi,

Static analysis with Coverity has picked up an issue with the following
commit:

commit 65c29dbb19b2451990c5c477fef7ada3b8218f05
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Wed Dec 11 15:02:04 2019 +0000

    drm/i915: Use the i915_device name for identifying our request fences

In source drivers/gpu/drm/i915/i915_request.c and function
i915_fence_get_timeline_name there is the following:

	return to_request(fence)->gem_context->name ?: "[" DRIVER_NAME "]";

However name is an array: char name[TASK_COMM_LEN + 8], so it can never
be null, so the ternary operator will always return name and will never
reaturn "[" DRIVER_NAME "]".  Should it instead be checking if name[0]
is '\0' instead?

Colin