drm/i915: Don't restrict i915_wa_registers to BDW

We have CHV code that already makes the test obsolete. Besides, when
num_wa_regs is 0 (platforms not gathering that W/A data), we expose
something sensible already.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2636,11 +2636,6 @@ static int i915_wa_registers(struct seq_file *m, void *unused)
 	struct drm_device *dev = node->minor->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (!IS_BROADWELL(dev)) {
-		DRM_DEBUG_DRIVER("Workaround table not available !!\n");
-		return -EINVAL;
-	}
-
 	ret = mutex_lock_interruptible(&dev->struct_mutex);
 	if (ret)
 		return ret;