scsi: isci: Remove redundant check in isci_task_request_build()

sci_task_request_construct_ssp() has invariant return. Change this function
to void and get rid of unnecessary checks.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
Link: https://lore.kernel.org/r/20231128121159.2373975-1-artem.chernyshev@red-soft.ru


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>