pmem: Switch to copy_to_iter_mcsafe()

Use the machine check safe version of copy_to_iter() for the
->copy_to_iter() operation published by the pmem driver.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/pmem.c

@@ -267,7 +267,7 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
 static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
 		void *addr, size_t bytes, struct iov_iter *i)
 {
-	return copy_to_iter(addr, bytes, i);
+	return copy_to_iter_mcsafe(addr, bytes, i);
 }
 
 static const struct dax_operations pmem_dax_ops = {