drm/xe/mmio: move mmio_fini over to devm

Not valid to touch mmio once the device is removed, so make sure we
unmap on removal and not just when driver instance goes away. Also set
the mmio pointers to NULL to hopefully catch such issues more easily.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240522102143.128069-32-matthew.auld@intel.com

drivers/gpu/drm/xe/xe_mmio.c

@@ -390,13 +390,16 @@ void xe_mmio_probe_tiles(struct xe_device *xe)
 	}
 }
 
-static void mmio_fini(struct drm_device *drm, void *arg)
+static void mmio_fini(void *arg)
 {
 	struct xe_device *xe = arg;
 
 	pci_iounmap(to_pci_dev(xe->drm.dev), xe->mmio.regs);
 	if (xe->mem.vram.mapping)
 		iounmap(xe->mem.vram.mapping);
+
+	xe->mem.vram.mapping = NULL;
+	xe->mmio.regs = NULL;
 }
 
 int xe_mmio_init(struct xe_device *xe)
@@ -421,7 +424,7 @@ int xe_mmio_init(struct xe_device *xe)
 	root_tile->mmio.size = SZ_16M;
 	root_tile->mmio.regs = xe->mmio.regs;
 
-	return drmm_add_action_or_reset(&xe->drm, mmio_fini, xe);
+	return devm_add_action_or_reset(xe->drm.dev, mmio_fini, xe);
 }
 
 u8 xe_mmio_read8(struct xe_gt *gt, struct xe_reg reg)