[SCSI] qla2xxx: Disable MSI on qla24xx chips other than QLA2432.

On specific platforms, MSI is unreliable on some of the QLA24xx chips, resulting
in fatal I/O errors under load, as reported in <http://bugs.debian.org/572322

>
and by some RHEL customers.

Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>