mpt3sas: add missing curly braces

There are some missing curly braces on this if statement, so we end up
printing when we shouldn't.

Fixes: a470a51c ('mpt3sas: Handle active cable exception event')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Chaitra P B <chaitra.basappa@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>