hpsa: set the enclosure identifier to zero

This has only called from show_sas_rphy_enclosure_identifier().  The
caller expects that we set an identifier, otherwise it uses an
uninitialized variable.

[mkp: fixed typo]

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>