scsi: qla2xxx: remove some redundant pointer assignments

There are several local or function parameter pointers that are being
assigned NULL after a kfree where and these have no effect and hence can
be removed.

Fixes various cppcheck warnings:

"Assignment of function parameter has no effect outside the
function. Did you forget dereferencing it"

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>