[SCSI] pmcraid: disable msix and expand device config entry

Firmware requires a larger configuration entry size than the driver
currently allows, and MSI-X pretty much doesn't work with current FW,
so disable it for now.

Signed-off-by: Anil Ravindranath <anil_ravindranath@pmc-sierra.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>