scsi: initio: Remove redundant assignment to pointer scb

scsi: initio: Remove redundant assignment to pointer scb

The variable scb is assigned a value but it is never read. The assignment
is redundant and can be removed. Also replace the != NULL check with the
more usual non-null check idiom.

Cleans up clang scan build warning:

drivers/scsi/initio.c:1169:9: warning: Although the value stored to 'scb'
is used in the enclosing expression, the value is never actually read
from 'scb' [deadcode.DeadStores]

Link: https://lore.kernel.org/r/20220805114100.2339637-1-colin.i.king@gmail.com
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>