drm/i915/selftests: Careful not to flush hang_fini on error setups

Smatch spotted that we test at the start of hang_fini for a valid (h->gt
is only set after a request is created) but then used it regardless
later on.

v2: Alternatively, we do not need to check as we now always prime h->gt
in hang_init()

References: cb823ed9 ("drm/i915/gt: Use intel_gt as the primary object for handling resets")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190729085944.2179-1-chris@chris-wilson.co.uk