[SCSI] hpsa: Change memset using sizeof(ptr) to sizeof(*ptr)

Not at all sure this is correct or appropriate to change,
but this seems odd.

Found via coccinelle script

@@
type T;
T* ptr;
expression E1;
@@

* memset(E1, 0, sizeof(ptr));

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>