[SCSI] mptfusion: Set fw_events_off to 1 at driver load time.

fw_events_off is flag checking for driver to do Event handling or not.
Normally it should be OFF at the time of initialization. Only enable it at
the time of INTR enable of device first time. This will always occur only
after resource allocation.

ioc->fw_events_off = 1 is set in mpt_attach()

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>