scsi: libsas: Remove redundant assignment to variable res

The variable 'res' is being initialized with a value that is never read and
it is being updated later with a new value. The initialization is redundant
and can be removed.

Link: https://lore.kernel.org/r/20200722154404.959267-1-colin.king@canonical.com


Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Addresses-Coverity: ("Unused value")