hpsa: remove unused fields from struct ctlr_info

The fields "major", "max_outstanding", and "usage_count"
of struct ctlr_info were not used for anything.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Reviewed-by: Mike Miller <michael.miller@canonical.com>
Reviewed-by: Webb Scales <webb.scales@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>