hpsa: correct endian sparse warnings

Correct endiness issues reported by sparse. SA controllers are
little endian. This patch ensures endiness correctness.

Signed-off-by: Don Brace <don.brace@pmcs.com>
Reviewed-by: Scott Teel <scott.teel@pmcs.com>
Reviewed-by: Webb Scales <webbnh@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>