scsi: sym53c8xx_2: remove redundant assignment to retv

Variable retv is initialized to a value that is never read and it is
re-assigned later. The initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>