scsi: zfcp: spin_lock_irqsave() is not nestable

We accidentally overwrite the original saved value of "flags" so that we
can't re-enable IRQs at the end of the function.  Presumably this
function is mostly called with IRQs disabled or it would be obvious in
testing.

Fixes: aceeffbb ("zfcp: trace full payload of all SAN records (req,resp,iels)")
Cc: <stable@vger.kernel.org> #2.6.38+
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>