drm/i915: Fix some gcc warnings

Simple one:
drivers/gpu/drm/i915/i915_debugfs.c:2449:57: warning: Using plain integer as NULL pointer

And something a bit more peculiar:
drivers/gpu/drm/i915/i915_debugfs.c:4953:18: warning: Variable length array is used.
drivers/gpu/drm/i915/i915_debugfs.c:4953:32: warning: Variable length array is used.

We pass a 'const int' as the array size which results in the warning,
dropping the const gets rid of the warning. Weird, but I think getting
rid of the warnings is better than holding on to the const.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2446,7 +2446,7 @@ static int i915_guc_info(struct seq_file *m, void *data)
 	struct drm_device *dev = node->minor->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_guc guc;
-	struct i915_guc_client client = { .client_obj = 0 };
+	struct i915_guc_client client = {};
 	struct intel_engine_cs *ring;
 	enum intel_ring_id i;
 	u64 total = 0;
@@ -4948,7 +4948,7 @@ static void cherryview_sseu_device_status(struct drm_device *dev,
 					  struct sseu_dev_status *stat)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	const int ss_max = 2;
+	int ss_max = 2;
 	int ss;
 	u32 sig1[ss_max], sig2[ss_max];