drm/i915/drv: return -EIO instead of -1

Avoid using the incidental -EPERM. Return the -EIO directly from
i915_get_bridge_dev() instead of converting return values later.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1ee72c31963d8be98490cd78f7c1182ba4f54c13.1633000838.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -97,7 +97,7 @@ static int i915_get_bridge_dev(struct drm_i915_private *dev_priv)
 		pci_get_domain_bus_and_slot(domain, 0, PCI_DEVFN(0, 0));
 	if (!dev_priv->bridge_dev) {
 		drm_err(&dev_priv->drm, "bridge device not found\n");
-		return -1;
+		return -EIO;
 	}
 	return 0;
 }
@@ -409,8 +409,9 @@ static int i915_driver_mmio_probe(struct drm_i915_private *dev_priv)
 	if (i915_inject_probe_failure(dev_priv))
 		return -ENODEV;
 
-	if (i915_get_bridge_dev(dev_priv))
-		return -EIO;
+	ret = i915_get_bridge_dev(dev_priv);
+	if (ret < 0)
+		return ret;
 
 	ret = intel_uncore_init_mmio(&dev_priv->uncore);
 	if (ret < 0)