drm/i915/selftests: Fix uninitialized variable

Static code analysis tool identified struct lrc_timestamp data as being
uninitialized and then data.ce[] is being checked for NULL/negative
value in the error path. Initializing data variable fixes the issue.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200303142347.15696-1-aditya.swarup@intel.com

drivers/gpu/drm/i915/gt/selftest_lrc.c

@@ -4723,9 +4723,9 @@ static int __lrc_timestamp(const struct lrc_timestamp *arg, bool preempt)
 
 static int live_lrc_timestamp(void *arg)
 {
+	struct lrc_timestamp data = {};
 	struct intel_gt *gt = arg;
 	enum intel_engine_id id;
-	struct lrc_timestamp data;
 	const u32 poison[] = {
 		0,
 		S32_MAX,