It's an interesting question. Based on the below limitation listed in their official docs, I'm assuming the location of the file is purposefully not displayed in the metadata. Would be interested to know the answer though. 

Ref:- Use materialized views in Databricks SQL | Databricks on AWS

• The underlying files supporting materialized views might include data from upstream tables (including possible personally identifiable information) that do not appear in the materialized view definition. This data is automatically added to the underlying storage to support incremental refreshing of materialized views. Because the underlying files of a materialized view might risk exposing data from upstream tables not part of the materialized view schema, Databricks recommends not sharing the underlying storage with untrusted downstream consumers. For example, suppose the definition of a materialized view includes a COUNT(DISTINCT field_a) clause. Even though the materialized view definition only includes the aggregate COUNT DISTINCT clause, the underlying files will contain a list of the actual values of field_a.