[SCSI] qla2xxx: Do not take a second firmware dump when intentionally generating one.

When we are intentionally generating a firmware dump by executing the
MBC_GEN_SYSTEM_ERROR command, the command actually times out. The normal
course of action when a mailbox command times out is to take a firmware dump.
However, in this special case we do not want to do this since the
MBA_SYSTEM_ERR AEN already generates a firmware dump.

Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>