[SCSI] hpsa: make hpsa.hpsa_simple_mode=1 module parameter actually work

It's not enough to simple avoid putting the board into performant
mode, as we have to set up the interrupts differently, etc.  When
I originally tested this module parameter, I tested it incorrectly
without realizing it, and the driver was running in performant mode
the whole time unbeknownst to me.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>