esas2r: fix an oversight in setting return value

The patch moves an error code assigment to a 'default' case
in the previous switch statement.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Bradley Grove <bgrove@attotech.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>