drm/xe: Fix tile fini sequence

Only set tile->mmio.regs to NULL if not the root tile in tile_fini. The
root tile mmio regs is setup ealier in MMIO init thus it should be set
to NULL in mmio_fini.

Fixes: dd08ebf6 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240809232830.3302251-1-matthew.brost@intel.com

drivers/gpu/drm/xe/xe_mmio.c

@@ -30,7 +30,8 @@ static void tiles_fini(void *arg)
 	int id;
 
 	for_each_tile(tile, xe, id)
-		tile->mmio.regs = NULL;
+		if (tile != xe_device_get_root_tile(xe))
+			tile->mmio.regs = NULL;
 }
 
 /*
@@ -146,9 +147,11 @@ int xe_mmio_probe_tiles(struct xe_device *xe)
 static void mmio_fini(void *arg)
 {
 	struct xe_device *xe = arg;
+	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
 
 	pci_iounmap(to_pci_dev(xe->drm.dev), xe->mmio.regs);
 	xe->mmio.regs = NULL;
+	root_tile->mmio.regs = NULL;
 }
 
 int xe_mmio_init(struct xe_device *xe)