scsi: ipr: Remove NULL check before freeing function

Fix the following coccicheck warning:

drivers/scsi/ipr.c:9533:2-18: WARNING: NULL check before some freeing
functions is not needed.

Link: https://lore.kernel.org/r/20200418095903.35118-1-yanaijie@huawei.com


Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>