Remove field storage information when a field record is purged.
Called from field_purge_field() to allow the field storage module to remove field information when a field is being purged.
$field: The field being purged.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_field_storage_purge_field($field) {
$table_name = _field_sql_storage_tablename($field);
$revision_name = _field_sql_storage_revision_tablename($field);
db_drop_table($table_name);
db_drop_table($revision_name);
}