dax/bus.c: don't use down_write_killable for non-user processes

Change an instance of down_write_killable() to a simple down_write() where
there is no user process that might want to interrupt the operation.

Link: https://lkml.kernel.org/r/20240430-vv-dax_abi_fixes-v3-3-e3dcd755774c@intel.com
Fixes: c05ae9d ("dax/bus.c: replace driver-core lock usage by a local rwsem")
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/dax/bus.c

@@ -1540,12 +1540,8 @@ static struct dev_dax *__devm_create_dev_dax(struct dev_dax_data *data)
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
 {
 	struct dev_dax *dev_dax;
-	int rc;
-
-	rc = down_write_killable(&dax_region_rwsem);
-	if (rc)
-		return ERR_PTR(rc);
 
+	down_write(&dax_region_rwsem);
 	dev_dax = __devm_create_dev_dax(data);
 	up_write(&dax_region_rwsem);