If nobody has enabled the relay, we're not comunicating with GuC, which
means that the stats don't have any meaning. Let's also remove interrupt
counter and tidy the debugfs formatting.

v2: Correct stats accounting (Sagar)
v3: Corrected one more error in stats accounting, move relay_enabled (Sagar)
Signed-off-by: NMichał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: NSagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180319095348.9716-9-michal.winiarski@intel.com